问题 选择题

西瓜之所以甘甜可口,主要是因为西瓜的(  )含有大量的糖分.

A.细胞壁

B.细胞膜

C.细胞液

D.细胞核

答案

A、细胞壁位于细胞的最外面,起到保护和支持作用,不符合题意.

B、细胞膜能控制物质的进出,也有保护作用,不符合题意.

C、液泡中含有细胞液,有各种味道的物质以及营养物质,如各种蔬果汁中含各种有味道的物质以及丰富的营养物质,就是来自于细胞中液泡的细胞液,符合题意.

D、细胞核内含遗传物质,对生物的遗传具有重要的意义,不符合题意.

故选:C

单项选择题
阅读理解

阅读理解。

     Winter's short days are more than cold. For many people, winter depression, the most common type

of Seasonal Affective Disorder(SAD), is as much a part of the reason as hats and scarves (围巾).

     Winter serious SAD sufferers may need medical treatment. Those feeling a little blue can help themselves

by sticking to a healthy lifestyle. Here are some tips:

     Pace yourself. Don't expect to do everything you normally can. Set a realistic schedule. Don't listen to

negative thinking, like blaming yourself or expecting to fail.

     Get involved in activities that make you feel good or feel like you've achieved something. For example,

play table tennis or badminton.

     If you are feeling depressed, you may feel like staying away from friends. Yet this is a time when a

friend's support can be helpful. Call them regularly. Remember, the more we put off calling or visiting a

friend, the harder it is to rebuild a friendship.

     Think clearly about what's wrong or right. Instead of giving in to vague feelings of sadness, look at

your problems objectively. Break down problems into specific issues that you can work on.

    Regular exercise helps to prevent and ease depression.

    Eat well. Studies show that a healthy diet can help to maintain(keep) a healthy body and mind. The

vitamins, minerals and micro-nutrients found in a balanced diet may help our bodies to produce feel-good

hormones (荷尔蒙).Foods containing chemicals to help produce feel-good hormones include bananas,

turkey, nuts and seeds. Eat at least five pieces of fruit and vegetables every day. P.S.Symptoms (症状)

of SAD: No interests or pleasure in things you used to enjoy Increased need for sleep A change in eating

habits, especially an appetite for sweet or starchy (含淀粉的) foods Weight gain A heavy feeling in the

arms or legs A drop in energy level Difficulty in concentrating Overly emotional Avoidance of friends and

social situations Frequent feelings of guilt Long-term feelings of hopelessness, and physical problems, such

as headaches

1.The writer of the passage agrees that ______.

A. the cold in winter makes us suffer from SAD

B. hats and scarves are as important as SAD

C. everyone of us meets SAD in winter

D. we are blue mainly because of short days in winter

2. It can be inferred that ______.

A. a more darkness will make us sad

B. we should wear hats and scarves in winter

C. a healthy lifestyle prevents us from serious SAD

D. staying away from friends makes us depressed

3. When we pace ourselves, we ______.

A. don't do anything we can

B. make a practical plan

C. expect to succeed in nothing

D. think something of guilt

4. The passage includes the following EXCEPT _____.

A. the earlier we meet friends, the easier it is to rebuild a friendship

B. if we give up to unclear feelings of sadness, we'll be caught in the SAD

C. playing table tennis helps us achieve whatever we want

D. feel-good hormones from a balanced diet can help keep a healthy body