问题 填空题
已知两个命题,如果A是B的充分条件,那么B是A的______条件,如果A是B的充分必要条件,那么
.
B
.
A
的______条件.
答案

如果A是B的充分条件,

那么B是A的必要条件.

若A是B的充分必要条件,

则A?B为真命题,

根据互为逆否命题的真假性相同可得

¬B?¬A为真命题,

.
B
.
A
的充要条件

故答案为:必要条件,充要条件.

阅读理解

阅读理解

     I first went to Harrow in the summer term. The school had the biggest swimming pool I had ever seen.

It was a good joke to come up behind a naked boy, and push him into the pool. I made quite a habit of

this with boys of my own size or less.

     One day I saw a boy wrapped in a towel on the side of the pool. He was no bigger than I was, so I

thought him a fair game. Coming secretly behind,I pushed him in,holding on to his towel so that it would

not get wet. I was surprised to see an angry face come out from the water, and a being of great strength

making its way by fierce strokes(猛力地划)  to the shore. I fled, but in vain. He overtook me, seized me

violently,and threw me into the deepest part of the pool. I soon climbed out on the other side, and found

myself surrounded by a crowd of younger boys. "Do you know what you have done?" they said, "It's

Amery;he is in Grade Six. He is champion at gym; he has got his football honor. "

    I was frightened and felt ashamed. How could I tell his position when he was wrapped in a bath towel

and so small? 1 decided to apologize immediately. "I am sorry, "I said,"I mistook you for a Grade Four

boy. You are so small. "He didn't seem pleased at all, so I added in a most brilliant word, "My father,

who is a great man, is also small. "At this he laughed, and after some general words about my rude

behavior and how I had better be careful in the future, signified the incident was closed.

1. The writer thought Amery "a fair game" because the boy__________.

A. looked like an animal

B. was fond of games

C. was of similar size

D. was good at sports

2. The writer felt "ashamed" because__________. 

A. he was laughed at by other boys

B. Amery turned out to be in the same grade

C. he pushed Amery hard and hurt him

D. he played a joke on an outstanding athlete

3. By saying "My father, who is a great man, is also small", the write __________.

A. tried to please Amery

B. challenged Amery

C. threatened Amery

D. admired his father

4. Which of the following is TRUE?  

A. The writer could run faster than Amery.

B. The writer liked playing jokes on boys of all sizes.

C. Amery was a student in Grade Four.

D. Amery forgave the writer for his rude behavior.

单项选择题