单项选择题

关于维生素C的性质
有关维生素C的性状不正确的是

A.白色结晶或结晶性粉末
B．无臭
C．不易溶于水
D．味酸
E．显酸性
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根据短文回答 23～30 题。 Can Mobile Phones Cause Disease? 1 'Mobile phone killed my man。'screamed one headline last year.Also came claims that an unpublished study had found that mobile phones cause memory loss.And a British newspaper devoid its front page to a picture supposedly(假定地)showing how mobile phones heat the brain.2 For anyone who uses a mobile phone,these are worrying times.But speak to the scientists whose work is the focus of these scares and you will hear a different story.According to them,there is no evidence that mobile phones cause cancer or any other illness in people.3 What we do have,however, are some results suggesting that mobile phones' emissions have a variety of strange effects on living tissue that can't be explained by the general radiation biology.And it's only when the questions raised by these experiments are answered that we' be able to say for sure what mobile phones might be doing to the head.4 0ne of the odd effects comes from the now famous' memory loss' study.Alan Price and his colleagues at the University of Bristol placed a device that imitated the microwave emissions of mobile phones to the left ear of volunteers.The volunteers were just as good at recalling words and pictures they had been shown on a computer screen whether or not the device was switched on.Preece says he still can't comment Ol3 the effects of using a mobile phone' for years on end.But he rules out the suggestion that mobile phones have an immediate effect on our cognitive abilities.'I'm pretty sure there is no effect on short-term memory,' he says.5 Another expert,Tatters all,remarked that his latest findings have removed fears about memory loss.One result,for instance,suggests that nerve cell synapses(突触)exposed to microwaves become more-rather than less-receptive(感受的)to undergoing changes linked to memory formation.6 Hopefully, microwaves might turn out to be good for you.It sounds crazy, but a couple of years ago a team led by William Aden at the Veterans Affairs Medical Center in California,found that mice exposed to microwaves for two hours a day were less likely to develop brain tumours when given a cancer-causing chemical. 第 23 题 Paragraphs 2_______________A．Bad ResultsB．Widespread OppositionC．Groundless AnxietyD．No Effect on Short-term MemoryE．Mysterious EffectsF．Further Reassurance
A.Also
B.And
C.
2
D.But
E.According
F.
3
G.And
H.
4
I.Alan
J.The
K.Preece
L.But
M.'I'm
N.
5
O.One
P.
6
Q.It
R.Bad
S.Widespread
T.Groundless
U.No
V.Mysterious
W.Further
单项选择题
根据短文回答 23～30 题。 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~C than when kept at 26~C． 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 produce 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. 第 23 题 Paragraph 2______________A．Control of RespirationB．Beauty of Fresh Cut FlowersC．Role of RespirationD．Most Important Aspect of Flower CareE．Need for Clean WaterF．Ways of Stopping Respiration
A.
2
B.
3
C.
4
D.
5
E.Control
F.Beauty
G.Role
H.Most
I.Need
J.Ways
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