机件上某尺寸为500mm，图样采用1：2的比例，则图样中该尺寸应标注为()。A．25

阅读理解。

     Proverbs are quite common in spoken English. We don't normally put them in a composition or a letter.

Sometimes it is helpful if you know what common proverbs mean. Here are a few examples.

     1) "Once bitten, twice shy." If a dog bites me, I shall be twice as careful in future when I see it. This

proverb is also used to apply to many things and not only to dogs. If you have been cheated at a shop, you

will not go the same shop again.

     2) "A bird in the hand is worth two in the bush." If I am a hunter, trying to catch birds, it is better to

catch one than to see two birds in a bush but not able to catch them. Thus this means that what you have

already got is better than the chance of being able to get something bigger in future.

     3) "Too many cooks spoil the broth (soup)". When too many people do something, they get in each other's

way and do a bad job.

     4) "To pour oil on troubled waters" is to try to calm things down. Oil is lighter than water. If a ship is in

trouble at sea, another ship may come to help it. The second ship can send small boats to rescue people.

However, it may first pour oil on the sea to make the sea less rough.

     5) "Don't be a dog in a manger( 槽 )" means " Don't be selfish." In a stable ( 马房 ), the manger is the

place where the horse's food is put. Sometimes a dog will sleep in the manger and bark when a horse comes

to get its food. The dog does want to eat the lay in the manger but it will not let the horse eat it.

     6) "He is sitting on the fence" means that somebody will not say whether he is in favor of a plan or against

it. He is sitting on a fence between two opposing sides, perhaps waiting to see which side will win.

     7) "He who pays the piper calls the tune." A piper is a musician. The man who employs or pays a musician

can say what tunes the man will play. Thus this means that if a man provides the money for a plan, he can say

how it will be carried out.

     8) "You can't get blood out of a stone" means that you cannot get something from a person who has not

got any of the things you want. e. g. you cannot get a million dollars from a poor man.

1. Peter has a bicycle which is much too small for him but he does not want to let his younger brother

    ride on it. His mother is angry and says to him: ______.

A. You can't get blood out of a stone

B. Don't be a dog in a manger

C. The early bird gets the worm

D. To pour oil on troubled waters

2. Mr. Wang paid for a new school. Some people didn't like the design of the school but they

    didn't argue with Mr. Wang because ______.

A. he was sitting on the fence

B. once bitten, twice shy

C. he who pays the piper calls the tune

D. a bird in the hand is worth two in the bush

3. Mrs. Lin wanted to buy a new dress. Her husband suggested that she buy it from a shop near their home.

    Mrs. Lin disagreed because she had been cheated by that shop. So she said: "I won't go there again

     because ______."　

A. a bird in the hand is worth two in the bush

B. I am sitting on the fence

C. once bitten, twice shy

D. too many cooks spoil the broth

4. Mr. Brown had quite a good job in Hong Kong but he thought that if he went to Singapore, he might

    get a much better job with more money and a larger house. His wife didn't want him to leave his job

     in Hong Kong and she reminded him that ______.

A. a bird in the hand is worth two in the bush

B. too many cooks spoil the broth

C. you can not get blood out of a stone

以下哪项：不属于系统病史

A．与修复相关的系统疾病史

B．正在接受的全身性系统疾病治疗

C．系统疾病对口腔疾病的影响

D．药物对口腔疾病的影响

E．疾病发生时间

伤口是细菌入侵人体的入口。

《庄子•齐物论》提出“齐是非”和“是非莫辩”的思想。庄子说：我和你辩论，你胜了我，我果真就错了吗？我胜了你，你果真就错了吗？究竟谁对谁错，在你我两人之间是无法断定的。请第三者来，也无法断定是非。因为第三者如果持有与你我相同的意见，就没有资格断定；如果持有与你我不同的意见，也没有资格断定。

辨析：真理是因人而异的，所以真理是无法辨明的。