问题 选择题

下列应用中,属于增大受力面积减小压强的是(  )

A.切蛋糕的“刀”用很细的钢丝制成

B.很重的坦克安装履带

C.注射器的针头很尖

D.建筑设计时,“非承重墙”使用轻质(密度较小的)材料

答案

A、切蛋糕的“刀”用很细的钢丝制成目的是减小受力面积,增大压强,所以选项A不符合题意.

B、很重的坦克安装展带的目的是增大受力面积,减小压强,所以选项B符合题意.

C、注射器的针头很尖的目的是减小受力面积,增大压强,所以选项C不符合题意.

D、建筑设计时,“非承重墙”使用轻质(密度较小的)材料的目的是减小压力,减小压强,所以选项D不符合题意.

故选B.

阅读理解

阅读理解。

     "What's happened to the bottle of medicine?" He couldn't find it in this usual place on a table in the sitting

room." What have you done with it?" he asked his wife. She said she hadn't seen it, and told him it was

probably under his nose, if he'd only open his eyes and look.

     He went into their son's bedroom to read him his bedtime story. On the floor there lay a bottle, the one he'd

been looking for; but it was empty."David what have you done with those sweet tablets which were in that

bottle? Did you eat them?" David nodded."How many did you eat?" No reply. He called his wife. She came,

realized what had happened and went very white."There must have been twenty-five or thirty tablets left in the

bottle. He can't have taken them all," said the father, feeling rather amazed. They searched the whole room,

but there were no tablets on the floor, or in David's bed.

     David and his mother and father hurried to the nearest hospital. "Put the boy on the stomach pump at

once," said the doctor, as soon as he heard the facts. They could hear David crying as they sat in the waiting

room that was the worst of it, for they were wondering if the child was going to be all right, but unable to do

anything except wait. The crying stopped and the doctor came back."Lucky you brought him quickly. The

tablets don't have time to dissolve in his stomach, so we got them all out. He's going to be all right." They took

David home, and bought a medicine box with a lock on it the next day.

1. The bottle of medicine is most probably for _______.

A. the husband

B. the wife

C. the son

D. somebody else

2. We know from the passage that the sweet tablets _______.

A. are a kind of delicious sweet food

B. are used to make people's body stronger

C. are used for treating some kind of illness

D. are a kind of nurture (营养品) good for people's health

3. David must have eaten _______ of the tablets.

A. several

B. half

C. most

D. all

4. What would the father and mother do to prevent such a thing from happening again?

A. Throw the medicine away.

B. Put the medicine in a safer place.

C. Not buy such medicine again.

D. Tell the son to eat less of the medicine.

5. Which of the following is the best title (标题) of this passage?

A. An Empty Medicine Bottle.

B. The Missing Tablets.

C. The Son, The Trouble Maker.

D. Careless Parents.

单项选择题