Keeping Cut Flowers
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 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 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 litre of water. The water and solution should also be replaced each day.
23 Paragraph 2 .
24 Paragraph 3 .
25 Paragraph 4 .
26 Paragraph 5 .
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
27 A few simple facts will help you keep cut flowers .
28 Respiration plays a key role .
29 The aging of cut flowers can be slowed down .
30 Another important way to prolong the life of cut flowers is .
A by keeping its original shape and colour
B in the life of cut flowers
C to produce carbon dioxide
D for as long as possible
E by controlling temperature
F to replace the water and solution every day
答案：
23. D 24. C 25. A 26. E 27. D 28. B 29. E 30. F
解析：
23. D 第二段介绍了保持适宜的温度是养花中最重要的方面。
24. C 第三段介绍了花的呼吸作用，并讲了呼吸作用在花生长中的作用。
25. A 第四段介绍了通过控制温度来控制花的呼吸作用。
26. E 第五段介绍了插瓶花需要插在干净的水里，这也是保持花新鲜的重要方面。
27. D 文章第一段中提到记住几个简单的事实就可以保持花尽可能长久的新鲜。
28. B 从第三段可以得知呼吸作用在插瓶花的生命中起着重要作用。
29. E 第四段提到控制呼吸作用可以减缓花的衰老，而控制呼吸作用是通过控制温度实现的。
30. F 文章最后一段说明了干净的水可以更长久的保持插瓶花的新鲜，因此每天更换水和溶液可以延长插瓶花的寿命。
