问题 单项选择题

牙列缺失后,口腔内的解剖结构与正常人相比,最主要的不同是

A.切牙乳突的形态、大小发生变化
B.颤动线与腭小凹的位置发生变化
C.上、下颌弓与腭穹隆因牙列缺失而形成
D.唇、颊系带组织显著变化
E.牙槽嵴的萎缩

答案

参考答案:E

解析:维持天然牙生存的牙槽突是随着牙齿的生长和行使功能而发育和保持的。牙齿缺失后,牙槽突逐渐吸收形成牙槽嵴,牙槽嵴的吸收即行加快。随着牙槽嵴的吸收,上下颌骨逐渐失去原有形状和大小。牙槽嵴的吸收速度与缺失牙的原因、时间及骨质致密程度有关。

阅读理解

阅读理解。

    When the Americans were getting ready to send (送) their first men to the moon, an old Australian was

watching TV in a restaurant (饭店). There was an Englishman in the restaurant, too, and he said to the

Australian, "The Americans are clever, aren't they? They are going to send some men to the moon. It is a

very long way from our world (世界)."

     "Oh, that's nothing," the Australian answered quickly."Our country is going to send some people to the

sun in a few months. That's much farther away than the moon, you know."

     "Oh, yes, it is," the Englishman said,"but the sun is too hot for people to go to." The Australian laughed

and said,"We won't go to the sun in the day, of course. We'll go there at night."

1. Who were going to send their first men to the moon?

A. The Americans.

B. The Australians.

C. The Englishmen.

D. Nobody.

2. Where were the Australian and Englishman watching TV?

A. In the cinema.

B. Outside a shop.

C. In a restaurant.

D. In an office.

3. The Englishman thought______.

A. the Americans were clever

B. the Australians were clever

C. the Englishmen were clever

D. the white people were clever

4. Both the Englishmen and the Australian knew that ______.

A. the moon was much farther away from our earth than the sun

B. the sun was much farther away from our earth than the moon

C. the sun was much hotter in the day than at night

D. the sun was much hotter at night than in the day

5. The Australian thought that ______.

A. the sun was very hot at night

B. the sun was too cold for people to go to at night

C. the sun is farther away at night

D. people can land on the sun at night

选择题