搜题请搜索小程序“爱下问搜题”
问题 选择题

n（n-1）（n-2）•…•4等于（　　）

A．Pn4

B．n!-4!

C．Pnn-4

D．Pnn-3

答案

由题意，n（n-1）（n-2）•…•4=

n(n-1)(n-2)•…•4•3•2•1
3•2•1
=
Pn-3n
，

故选D．

填空题

根据句意完成句子。

1. Many students ask for advice about _____ their English.

2. Yi Wen has tried _____ food in a hotel in Nanjing.

3. She was _____of making a daisy chain when suddenly a rabbit ran by her.

4. Have you heard the _____news?

5. That _____interesting.

6. How long have you _____ English?

7. He _____ going to school a few years ago.

8. They can't go to school _____ the help of Project Hope.

9. I think she'll like _____ Beijing Opera.

10. The most famous _____ were Johann Strauss and Mozart.
查看答案
单项选择题

《电气化铁路接触网零部件》（TB/2075.1~2075.54-2002）规定，接地线连接线夹螺栓紧固力矩为（）

A、59N•mN

B、56N•m

C、60N•m

D、44N•m
查看答案