[单选题]

Keeping Cut Flowers(鲜切花)

While everybodyenjoys fresh cut flowers around his/her house,few people know how to keep themfor as long as possible .This may be done by keeping in mind a few

simple facts.

2. An importantthing to remember about cut flowers is that they are sensitive totemperature.For example,studies have shown that cut carnations(康乃馨)retain their

freshness eighttimes lon-ger when kept at 12℃than when kept at 26℃.Keeping freshlyharvested flowers at the right tem-peratures is probably the most importantaspect

of flower care.

3. Flowers are notintended by nature to live very long.Their biological purpose is simply toat-tract birds or insects,such as bees,for pollination(授粉).After that,they

quickly dry up anddie. The process by which flowers consume oxygen and produce carbon dioxide(二氧化碳), called respiration(呼吸),generates the energy the

flower needs to givethe flower its shape and color. The making of seeds also depends on thisenergy.While all living things respire,flowers have a high level ofrespiration.A

result of all thisrespiration is heat,and for flowers the level of heat relative to the mass ofthe flower is very high.Respiration also brings about the eventual death of the

flower. Thus thegreater the level of respiration,the sooner the flower dies.

4. How,then,tocontrol the rate at which flowers die?By controlling respiration.How isrespi-ration controlled?By controlling temperature .We know that respirationproduces

heat,but there-verse(相反的过程)is alsotrue. Thus by maintaining low temperatures , respiration is reduced and the cutflower will age more slowly.

5. Another vitalfactor in keeping cut flowers is the quality of the water in which they areplaced. Flowers find it difficult to“drink”water that is dirty or otherwise

polluted.Even whenwater looks and smells clean,it almost certainly contains harmful substances thatcan endanger the flowers. To rid the water of these unwanted

substances,household chlorine bleach(漂白剂)can be used in small quantities.It is recommended that 15 drops ofchlorine bleach(at 4%solution)be add-ed to each litre of

water. The water andsolution should also be replaced each day.

Paragraph3________

A.Control ofRespiration

B. Beauty of FreshCut Flowers

C. Role ofRespiration

D. Most ImportantAspect of Flower Care

E. Need forCleanwater

参考答案与解析:

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