概括大意与完成句子
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. 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.
The aging of cut flowers can be slowed down__________.
A、by keeping its original shape and color
B、by replacing the water and solution every day
C、to produce carbon dioxide
D、by controlling temperature
【正确答案】 D
【答案解析】 本段文字主要讲了温度对鲜切花的重要性，控制温度是延缓切花枯萎的途径。答案为D。
