阅读下面这篇短文，短文后有2项测试任务： (1) 第23-26题要求从所给的6个选项中为第2-5段每段选择1个最佳标题； (2)
第27-30题要求从所给的6个选项中选择4个正确的选项，分别完成每个句子。 Keeping Cut Flowers 1
While everybody enjoys fresh cut flowers around his 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. 2 An important thing to remember about
cut flowers is that they are sensitive to temperature. For example, studies have
shown that cut carnations (康乃馨) 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. 3 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 (授粉). After that, they quickly dry up and die. 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 give the flower its
shape and color. 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 heat 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. 4 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 reduced and the cut
flower will age more slowly. 5 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 polluted.
Even when water looks and smells clean, it almost certainly contains harmful
substances that can endanger the flowers. To rid the water of these unwanted
substances, household chlorine bleach (含氯漂白剂) can be used in small quantities.
It is recommended that 15 drops of chlorine bleach (at 4% solution) be added to
each liter of water. The water and solution should also be replaced each
day.
A. Control of Respiration B. Beauty of Fresh
Cut Flowers C. Role of Respiration D. Most
Important Aspect of Flower Care E. Need for Clean
Water F. Ways of Stopping Respiration Paragraph 2 ______.