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Keeping Cut Flowers
While everybody enjoys fresh cut flowers around their house, few
people know how
to keep them for as long as possible. This may be done by keeping in
mind a few simple
facts.
An important thing to remember about cut flowers is that they are
sensitive to
temperature. For example, studies have shown that cut carnations
retain their
freshness eight times longer when kept at 12℃ than when kept at
26℃. Keeping
freshly harvested flowers at the right temperatures is probably the
most important
aspect of flower care.
Flowers are not intended by nature to live very long. Their
biological purpose is
simply to attract birds or insects, such as bees, for pollination.
After that, they
quickly wither and die. The process by which flowers consume oxygen
and emit carbon
dioxide, called respiration,generates the energy the flower needs to
give the flower
its shape and colour. The making of seeds also depends on this
energy. While all
living things respire, flowers have a high level of respiration. A
result of all
this respiration is heat, and for flowers, the level of he at
relative to the mass
of the flower is very high. Respiration also brings about the
eventual death of the
flower, thus the greater the level of respiration, the sooner the
flower dies.
How, then to control the rate at which flowers die? By controlling
respiration.
How is respiration controlled? By controlling temperature. We know
that respiration
produces heat, but the reverse is also true. Thus by maintaining low
temperatures,
respiration is minimised and the cut flower will age more slowly.
(Tropic
al flowers are an exception to this rule; they prefer warmer
temperatures.)
Cooler temperatures also have the benefit of preserving the water
content of the
flower, which helps to slow down ageing as well. This brings us to
another important
aspect of cut flower care: humidity. The average air-conditioned
room has a relative
humidity of 65%, which contributes to greater water loss in the
flower. Flowers are
less likely to dry out if humidity levels are 90_95%, but this may
be unrealistic
unless you live in the tropics or subtropics.
Yet another vital factor in keeping cut flowers is the quality of
the water in which
they are placed. Flowers find it difficult to `drink' water that is
dirty or otherwise
contaminated. Even when water looks and smells clean, it almost
certainly contains
bacteria and fungi that can endanger the flowers. To rid the water
of these unwanted
germs, household chlorine bleach can be used in small quantities. It
is recommended
that 15 drops of chlorine bleach (at 4% solution )be added to each
litre of water.
The water and solution should also be replaced each day.
When going to buy cut flowers, look for ones that have not been
kept (by the flower
shop) in direct sunlight or strong wind. If the flowers are not
freshly harvested,
ask whether they have been stored in a refrigerated coolroom.
1 The author of Keeping Cut Flowers believes flower care is
dependent on
three main factors. one of them is temperature. What are the other
TWO?
2 A DIFFERENCE OF 140C can extend the life of carnations by up to ()
times.
3 () and () are two aspects of a flower's appearance that depend on
respiration.
KEY:1 humidity AND water quality(either order) 2 8/eight 3 shape
AND colour(either order)
key:5 controlling temperature//maintaining low temperatures//cooler
temperatures
6 water content 7 age(more)slowly 8 tropical
Wild Foods Of Australia
Over 120 years ago, the English botanist J.D.Hooker, writing
of Australian edible
plants. suggested that many of them were `eatable but not worth
eating'. Nevertheless,
the Australian flora, together with the fauna, supported the
Aboriginal
people well before the arrival of Europeans. The Aborigines
were not farmers an
d were wholly dependent for life on the wild products around them.
They learned
to eat, often after treatment, a wide variety of plants.
The conquering Europeans displaced the Aborigines, killing
many, driving others
from their traditional tribal lands. and eventually settling many of
the tribal
remnants on government reserves, where flour and beef replaced
nardoo and wallaby
as staple foods. And so, gradually, the vast store of knowledge,
accumulated
over thousands of years, fell into disuse. Much was lost.
However, a few European men took an intelligent and even
respectful interest in
the people who were being displaced. Explorers, missionaries,
botanists,
naturalists and government officials observed, recorded and.
fortunately in some
cases, published. Today, we can draw on these publications to form
the main basis
of our knowledge of the edible, natural products of Australia. The
picture is no
doubt mostly incomplete. We can only speculate on the number of
edible plants on
which no observation was recorded.
Not all our information on the subject comes from the
Aborigines. Times were hard
in the early days of European settlement, and traditional foods were
often in
short supply or impossibly expensive for a pioneer trying to
establish a farm in
the bush. And so necessity led to experimentation, just as it must
have done for
the Aborigines, and experimentation led to some lucky results. So
far as is known,
the Aborigines made no use of Leptospermum or Dodonaea as
food plants,
Yet the early settlers found that one could be used as a substitute
for tea and
the other for hops. These plants are not closely related to the
species they replaced,
so their use was not based on botanical observation, Probably some
experiments had
less happy endings; L.J.Webb has used the expression `eat, die and
learn' in
connection with the Aboriginal experimentation, but it was the
successful attempts
that became widely known. It is possible the edibility of some
native plants used
by the Aborigines was discovered independently by the European
settlers or their
descendants.
Explorers making long expeditions found it impossible to
carry sufficient food for
the whole journey and were forced to rely, in part, on food that
they could find
on the way, Still another source of information comes from the
practice in other
countries. There are many species from northern Australia which
occur also
in southeast Asia, where they are used for food.
In general, those Aborigines living in the dry inland areas
were largely dependent
for their vegetable foods on seed such as those of grasses, acacias
and eucalypts.
They ground these seeds between flat stones to make a coarse flour.
Tribes
on the coast, and particularly those in the vicinity of coastal
rainforests, had
a more varied vegetable diet with a higher proportion of fruits and
tubers. Some
of the coastal plants, even if they had grown inland, probably would
have been
unavailable as food since they required prolonged washing or soaking
to render
them non-poisonous: many of the inland tribes could not obtain water
in the
quantities necessary for such treatment. There was also considerable
variation in
the edible plants available to Aborigines in different latitudes. In
general, the
people who lived in the moist tropical areas enjoyed a much greater
variety than
those in the southern part of Australia.
With all the hundreds of plant species used for food by the
Australian Aborigines,
it is perhaps surprising that only one, the Queensland nut, has
entered into
commercial cultivation as food plant. The reason for this probably
does not lie
with an intrinsic lack of potential in Australian flora, but rather
with the lack
of exploitation of this potential. In Europe and Asia, for example,
the main food
plants have had the benefit of many centuries of selection and
hybridisation, which
has led to the production of forms vastly superior to those in the
wild. Before the
Europeans came, the Aborigines practised no agriculture and so there
was no
opportunity for such improvement, either deliberate or unconscious,
in the quality
of the edible plants.
Since 1788, there a has, of course, been opportunity for
selection of Australian
food plants which might have led to the production of varieties that
were worth
cultivating. But Australian plants have probably `missed the bus'.
Food plants
from other regions were already so far in advance after a long
tradition of
cultivation that it seemed hardly worth starting work on Australian
species.
Undoubtedly, the native raspberry, for example, could, with suitable
selection and
breeding programs, be made to yield a high-class fruit; but
Australians already enjoy
good raspberries from other areas of the world and unless some
dedicated amateur
plant breeder takes up the task, the Australian raspberries are
likely to remain
unimproved.
And so, today, as the choice of which food plants to
cultivate in Australia has
been largely decided. and as there is little chance of being lost
for long
periods in the bush, our interest in the subject of Australian food
plants tends
to relate to natural history rather than to practical necessity.
26 Most of the pre-Europe an Aboriginal
NO
knowledge of wild foods has been recovered
27 There were few food plants unknown to
NOT GIVEN
pre-European Aborigines
28 Europeans learned all of what they knew of edible NO
wild plants from Aborigines
29 Dodonaea is an example of a plant used for food
NO
by both pre-European Aborigines and European
settlers
30 Some Australia food plants are botanically
YES
related to plants from Aborigines
31 Pre-European Aboriginal tribes close to the coast had
YES
access to a greater variety of food plants than further
inland
32 Some species of coastal food plants were also found inland
NOT GIVEN
34 Experimentation with plants...
A depended largely an botanical observation
B was unavoidable for early settlers in all parts of Australia
C led Aborigines to adopt Leptospermum as a food plant
D sometimes had unfortunate result for Aborigines
35 Wild plant use by Aborigines...
A was limited to dry regions
B was restricted to seed
C sometimes required the use of tools
D was more prevalent in the southern part of Australia
KEY:34 D 35 C
Despite the large number of wild plants that could be used for
food. Only one,
the…(36)…is being Grown as a cash crop. Other edible plants in
Australia, however
much potential they have for cultivation. Had not gone through the
lengthy process
of …(37)…that would allow their exploitation. Because Aborigines
were not farmers.
This species such as …(38)…which would be an agricultural
success had it not had to
compete with established European varieties at the time of European
settlement are of
no commercial value.
KEY:36 Queenland nut 37
selection//hybridization//improvement//breeding
38 (native) raspberry
NEW-AGE TRANSPORT
Computerised design.advanced materials and new technologies are
being used to
Produce machines of a type never seen before.
It looks as if it came straight from the set of Star Wars. It has
four-wheel drive
and rises above rocky surfaces. It lowers and raises its nose when
going up and down
hills. And when it comes to river, it turns amphibious: two
hydrojets power it along
by blasting water under its body. There is room for two passengers
and a driver,
who sit inside a glass bubble operating electronic, aircraft-type
controls. A
vehicle so daring on land and water needs windscreen wipers-but it
doesn't have any.
Water molecules are disintegrated on the screen's surface by
ultrasonic sensors.
This unusual vehicle is the Racoon. It is an invention not of
Hollywood but of Renault,
a rather conservative French state-owned carmaker, better known for
its family
hatchbacks. Renault built the Racoon to explore new freedoms for
designers and
engineers created by advances in materials and manufacturing
processes. Renault is
thinking about startlingly different cars; other producers have
radical new ideas
for trains, boats and aeroplanes.
The first of the new freedoms is in design. Powerful
computer-aided design (CAD)
systems can replace with a click of a computer mouse hours of
laborious work done
on thousands of drawing boards. So new products, no matter how
complicated, can be
developed much faster. For the first time, Boeing will not have to
build a giant
replica of its new airliner, the 777, to make sure all the bits fit
together. Its
CAD system will take care of that.
But Renault is taking CAD further. It claims the Racoon is the
world's frist vehicle
to be designed within the digitised world of virtual reality.
Complex programs were
used to simulate the vehicle and the terrain that it was expected to
cross. This
allowed a team led by Patrick Le Quement, Renault's industrialdesign
director, to
"drive" it long before a prototype existed.
Renault is not alone in thinking that virtual reality will
transform automotive
design. In Detroit. Ford is also investigating its potential. Jack
Telnac. The firm's
head of design, would like designers in different parts of the world
to work more
closely together, linked by computers. They would do more than style
cars. Virtual
reality will allow engineers to peer inside the working parts of
vehicle. Designers
will watch bearings move. oil flow, gears mesh and hydraulics pump.
As these tech
niques catch on. even stranger vehicles are likely to come along.
Transforming these creations from virtual reality to actual
reality will also be
come easier, especially with advances in materials. Firms that once
bashed every
thing out of steel now find that new alloys or composite materials
(which can be
made from mixtures of plastic, resin, ceramics and metals,
reinforced with fibres
such as glass or carbon) are changing the fules of manufacturing. At
the same
time, old materials keep getting better, as their producers try to
secure their
place in the factory of the furture. This competition is increasing
the pace of
development of all materials.
One company in this field is Scaled Composites. It was started in
1982 by Burt Rutan.
An aviator who has devised many unusual aircraft. His company
develops and tests
prototypes that have ranged from business aircraft to air racers. It
has also worked
on composites sails for the American's Cup yacht race and on General
Motors's
Ultralite. a 100-miles-per-gallon experimental family car built from
carton fibre.
Again, the Racoon reflects this race between the old and the new. It
uses conventional
steek and what Renault describes as a new "high-limit elastic
steel"in its chasis.
This steel is 30% lighter than the usual kind. The Racoon also has
parts made from
composites. Renault plans to replace the petrol engine with a small
gas turbine.
which could be made from heat-resisting ceramics. and use it to run
a generator that
would provide power for electric motors at each wheel.
With composites it is possible to build many different
parts into a single
component.Fiat, Italy's biggest car madder has worked out that it
could reduce the
number of components needed in one of its car bodies from 150 to 16
by using a
composite shell rather than one made of steel. Aircraft and cars may
increasingly
be assembled as if they were plastic kits.
Advances in engine technology also make cars lighter. The
Ultralite, which Scaled
Composites helped to design for General Motors, use a two-stoke
engine in a "power
pod"at the rear of the vehicle. The engine has been developed
from an East German
design and weight 40% less than a conventional engine but produces
as much power.
It is expected to run cleanly enough to qualify as an ultra-low
emissions vehicle
under California's tough new rules.
4 How did Renault test drive the Racoon?
A over rocky terrain
B in actual reality
C over French country roads
D in virtual reality
key: D
6 One future design feature of the Racoon might be a ...
7 In the future cars might be put together like...
8 The advantage of the Ultralite engine is 40%...than other car
engines
key: 6 (small)gas turbine/generation/(elastic) steel chassis 7
plastic kits 8 lighter
9 a power pod
GM
10 electronic controls R
11 a composite body F
12 elastic steel R
13 aircraft prototypes SC
14 ultrasonic sensors R
GETTING GIRLS ON-LINE
When Nancy Leveson, now a computer science professor at the
University of Washington,
was teaching math at a California high school, her best student also
happened to
be one of the prettiest and most popular girls around. And when the
girl got the
highest score on a test, Leveson thought nothing of announcing the
achievement while
handing back the papers. As soon as the class ended, though, the
distraught student
approached. She begged her teacher never, ever to embarrass her like
that again.
The incident happened nearly 20 years ago, but Leveson notes that
little has changed.
Now, as then, too many teenage girls feel uncomfortable and even
unwelcome in the
realms of math, science and computing. Research shows that girls who
are gifted in
these subjects in elementary school begin to shy away from them by
the seventh grade.
Eventually, they convince themselves that these are male domains.
"By saying only
men are good at these things, you make the women who are good at
them seem like
freaks," says leveson.
Increasingly, however, educators are trying to reverse the
process by retraining
teachers and redirecting students. Funded with more that $1 million
by the National
Science Foundation (NSF) and seven corporations, Computer Equity
Expert Project
(CEEP) showed 200 math and computer-science teachers how to
recognise and eliminate
gender bias in their classrooms. CEEP urged teachers to bring more
girls into the
world of computers by setting up mentoring programs with older
students and having
girls-only days at the school computer labs.
Both public and private schools are trying to close the
technology gap. Because
girls tend to do better in the sciences without the distraction of
boys, three
California schools have started girls-only math classes over the
last two years,
with promising results. Other schools are hooking up with colleges
for help and
inspiration.
But however wonderful the subject looks in high school, interest
often diminishes
in college, where women earned only 30% of the undergraduate degrees
awarded in
computer science in 1991, and 16% in engineering in 1993, as opposed
to medical school,
where women make up 36% of total enrolment. The proportion shrinks
still more at
the doctoral level, where women receive only 15% of computer science
PhDs and under
10% of engineering PhDs.
Many college women are turned off by the macho swagger of
technojocks at schools
like MIT, where staying awake for three days to perfect a piece of
software is seen
as a test of virility. That kind of attitude "sets cultural
parameters not just
for MIT but for the intense nature of the computer culture
everywhere, "says Steven
Levy, author of Hackers: Heroes of the Computer Revolution.As a
result, it's hard
to find female role models in computer science.
To keep women interested in the field, Nancy Leveson and a
colleague from the Un
iversity of British Columbia spearheaded a program that will match
20 female
undergraduates with faculty mentors around the country this summer,
thanks to a $
40 000 grant from the NSF.
In Rochester, NY, the Rochester Institute of Technology's Women
is Science,
Engineering and Math mentoring program aims to spark high school
girls' career
interests by linking 140 girls and professional women in a computer
network.
Coordinators, who hope to extend the four-month program to three
years, note the
intense interest shown by girls and women. "I can't keep the
mentors away," says
Carol O' Leary, who helped set the program up. "I was looking
for 40, and I have
67. Women are anxious to give of themselves."
Eventualy, these computer educators would like to make
gender-specific programs
obsolete, but that will happen only when computer-science education
becomes more
creative, according to Paula Rayman, director of Pathways for Women
in the Sciences,
a research program at Wellesley College. By way of example, Rayman
points
to her9_year_old daughter, Lily, whose fourth-grade class at the
Bowman Elementary
School in Lexington, Mass., is learning several sciences under
the guise
of bicycle repair. The kids aren't just fixing bikes but ingesting
knowledge about
mechanics, scientific history and the physics of motion. They're
also using their
computers to generate charts, graphs and databases. Children of both
sexes are eager
to work with computers because the machines are revealed as both
entertaining and
useful, not just as a source of boring drills or violent games,
which girls usually
find unappealing.
"When it comes to girls and computers," says Rayman,
"we've found that there
are three ingredients for user-friendliness: hands-on experience,
teamwork and
relevance." These ingredients, of course, would increase
anyone's mastery of
computers, as well as the usefulness of the machines. By trying to
do a better job
of teaching girls, computer scientists may learn quite a lot
themselves.
16 Females generally do best at math and science
A up to seventh grade
B when they feel comfortable and welcome in the course
C when they are teenagers
D when they can compete with males
18 Which of the following is true about women studying in
university?
A 10% studying engineering got PhDS
B 36% of total enrolments are in medical school
C 16% of undergraduate engineering degrees were awarded to women
D 30% studying computer science in 1991 got degrees
Question 19-22
Four individuals are mentiond in Reading Passage 2. Four whom are
the following statements true?
Write the appropriate letters in boxes 19-22 on your answer sheet.
NL Nancy Leveson SL Steve Levy
PR Paula Rayman CO Carol O'Leary
19 has a daughter
20 helper organize the mentor program
21 wrote a book
22 is head of the mentor program
Question 23-28
23 The overwhelmingly male computer culture repels many women..
24 The Rochester Institute of Technology is organizing a three-year
mentoring program for girls.
25 Special computer programs are being written for women.
27 Physics and history are two of the main subjects taught at
Bowman.
28 Computer scientists are likely to learn a lot from teaching
girls.
Key:16 A 18 C
19.PR 20.CO 21.SL 22.NL
23 YES 24 NO 25 NG 27 NO 28 YES
未完，请继续》》
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