问题 选择题

花生四烯酸即5,8,11,14-二十碳烯酸(含有四个碳碳双键),其分子式可表示为 C19H31COOH,是人体“必需脂肪酸“之一.以下关于它的说法中不正确的是(  )

A.每摩尔花生四烯酸最多可与4摩尔溴发生加成反应

B.它可以使酸性高锰酸钾溶液褪色

C.它可与乙醇发生酯化反应

D.它是食醋的主要成分

答案

A.花生四烯酸含有四个碳碳双键,1mol双键与1mol溴发生加成反应,则每摩尔花生四烯酸最多可与4摩尔溴发生加成反应,故A正确;

B.碳碳双键能被高锰酸钾溶液氧化,则可以使酸性高锰酸钾溶液褪色,故B正确;

C.含有羧基,能与乙醇发生酯化反应,故C正确;

D.食醋的主要成分为醋酸,结构简式为CH3COOH,故D错误;

故选D.

单项选择题
阅读理解

阅读理解。

     Occasional sleepwalking does not tend to present a problem and most children grow out of it. If it

happens every night and causes problems, then sleep disorder specialists suggest that parents spend a

week noting the time when sleepwalking tends to happen, and then gently wake the child about fifteen

minutes before this time. This will often break the cycle.

    So what should you do if you find your relative sleepwalking? For a start, they are in such a deep sleep

that they will probably not notice you, even if you try to wake them. If you do succeed in walking them,

they will become distressed. Everyone has experienced that feeling of confusion when the alarm awakens

you from deep sleep, instead of the lighter sleep we are usually experiencing by the time our alarms

sound. I once had the shock of being woken by a crash and found myself in the kitchen, standing

barefoot and surrounded by broken glass. I'd tried to get a glass of water while sleepwalking, but like

most sleepwalkers I failed to turn on the light, and had smashed the glass against the tap.

    Walking a sleepwalker will not cause them to have a heart attack, but the kindest thing to do is not try

to wake them at all. Lead them gently back to bed so that they do not hurt themselves. They will remain

deeply asleep, and it is likely that will not remember a thing in the morning.

1.What do the specialists advise the parents to do to avoid their children's sleepwalking?

A. Go to bed with their children at the same time.

B. Keep a record of the time when children wake up.

C. Take 15 minutes to wake children from sleepwalking.

D. Try some time to break the cycle of the sleepwalking.

2. When a sleepwalker is suddenly woken, he is most likely to   ___  .

A. die from heart attack    

B. do some cooking

C. feel lost    

D. become relaxed

3.What should we do to deal with a sleepwalking relative?

A. Do nothing but take him back to bed.

B. Try every means to wake him at once.

C. Leave your relative where he stays.

D. Send him to a specialist immediately.

4. What is the best title for the text? 

A. Sleep Disorder  

B. Sleepwalking    

C. Sleep Advice    

D. Sleepwalkers