问题 单项选择题

功能性活动保持器的适应证为

A.第二乳磨牙早失、第一恒磨牙萌出不足

B.第一乳磨牙早失

C.乳磨牙缺失两个以上或两侧乳磨牙缺失或伴有乳前牙缺失

D.两侧都存在第二乳磨牙或第一恒磨牙,近期内继承恒牙即将萌出

E.因龋齿或乳牙早失使间隙变小或消失

答案

参考答案:C

解析: 功能性活动保持器的适应证为乳磨牙缺失两个以上或两侧乳磨牙缺失或伴有乳前牙缺失;远中导板保持器适应证为第二乳磨牙早失、第一恒磨牙尚未萌出或萌出不足;丝圈保持器适应证为第一乳磨牙早失,或第一恒磨牙已经萌出,第二乳磨牙早失;舌弓保持器适应证为两侧都存在第二乳磨牙或第一恒磨牙,近期内继承恒牙即将萌出;间接扩展装置适应证为因龋齿或乳牙早失使间隙变小或消失,为恢复间隙以利继承恒牙萌出,常需要把变小或关闭的间隙开扩。故答案为 C。

单项选择题

Are you a man or a mouse When people ask this question they want to know (1) you think you are a (2) person or a coward. But you will never really know the answer to this question (3) you are tested in real life. Some people (4) they are brave but when they come face to face with real (5) , they act like cowards. Others think of themselves as cowards, but when they meet danger, they act like (6)

Lenny had always thought of himself as a (7) person. He got worried before examinations. He worried about his job and health. All he wanted in life was to be safe and healthy. (8) , on January 15th, 2002, a plane crashed into the Potomac River in Washington. Lenny went to the river to see what was happening. He saw a woman in the (9) water. Lenny did not feel afraid. He kept very (10) and did a very dangerous thing. He jumped into the Potomac, (11) to the woman, and kept her head (12) the water. Seventy-eight people died that day. Thanks to Lenny, it was not (13) .

When you are in a very (14) situation and feel afraid, the body automatically produces a chemical in the blood. The chemical is called adrenalin. (15) adrenalin in the blood system, you actually feel per and per and are (16) to fight or run away. However, when you are absolutely terrified, the body can produce too much adrenalin. When this (17) , the muscles become very hard and you find you (18) move at all. You are then paralyzed with fear. This is (19) when we are very frightened, we sometimes say we’re "petrified". This word comes from the Greek word "petros", which means "stone". We are (20) frightened that we become stonelike.

17()

A.gets 

B.disappears 

C.happens 

D.goes

单项选择题