问题 单项选择题

设变量x1,x2,…,x10的算术平均值为.若为定值,则诸xi(i=1,2,…,10)中可以任意取值的变量有( ).

A.10个

B.9个

C.2个

D.1个

E.0个

答案

参考答案:B

解析:
[解] .不难看出,因为x为定值·故只要x1,x2,…,x10中有9个任意取值,则余下的那个变量就完全确定了.
故本题应选B.

阅读理解

阅读理解

Mr. White works in an office. One day, when he had lunch, a friend came to visit him . They were very happy and talked a lot. Then they looked at the clock on the wall. It was time to go to office. He had to say goodbye to his friend and left. It was raining hard and the streets were wet. He drove too fast to see the red lights . And he couldn’t stop his car and hit a car in front of his. An old man got off and called out angrily, “ What are you doing? Do you want to hit me to death?”

“I’m sorry , sir,” said Mr. White . “I didn’t find the lights turned red.” Then he brought out a bottle of wine and gave it to the old man .

“ It’s very cold today , sir ,” said Mr. white . “Please drink a little , then you’ll be warmer.” The old man drank some wine and became happy. “I’m feeling much better now. Why don’t you drink any?” he asked.

I can’t drink anything now ,sir,” answered Mr. White.

I’m waiting for the policeman to come. Only drunkards (酒鬼) cause accidents, you know!”

小题1: The story happened________________.

A.in the morning

B.in the afternoon

C.in the evening

D.at night小题2:Mr White drove too fast because _______________

A.he was happy that day

B.he was good at drinking

C.there were few cars in the street

D.he was afraid to be late小题3:Mr White hit the car because  ________.

A.he didn’t see it

B.it was raining hard

C.he couldn’t stop his in time

D.he couldn’t drive at all.小题4: Mr. White gave a bottle of wine to the old man ________.

A.to put the blame onto the old man

B.to make him happy

C.to make him warm

D.to leave there before the policeman小题5:At last ___________________.

A.the old man felt much better

B.the old man was friendly to Mr. White

C.Mr. White drank some ,too.

D.Mr. White fooled the old man .

单项选择题