(1)第23-26题要求从所给的6个选项中为第2-5段选择1个最佳标题； (2)第27-30题要求从所给的6个选项中为每个句子确定1个最佳选项。
1 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. 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 ______.