问题 单项选择题

某分部工程双代号时标网络计划如下图所示,其中工作C的总时差和自由时差()天。

A.分别为1和0

B.均为1

C.分别为2和0

D.均为0

答案

参考答案:C

解析:

工作总时差等于本工作自由时差与其紧后工作的总时差之和的最小值,即 TFG=0+TFK=0+FFKF=0+2=2。工作C的自由时差就是谊工作箭线中波形线的水平投影长度,即为0。

阅读理解

阅读理解。

     The Internet has become part of teenage life. There's a report on 3 375 students in seven Chinese cities.

It says that 38% of them believe they use the Internet often. While most of them get useful information and

use the Internet to help in their studies, some are not using it in a good way. Many are playing online games

too much. A few even visit websites they should not look at. Bad things can happen if young people spend

too much time on the Internet.

     In order to help young people use the Internet in a good way, a textbook has been used in some Shanghai

middle schools this term. It uses real examples to teach students all about good ways of using the Internet.

It gives useful advice such as it's good to read news or find helpful information to study. Some students also

make online friends.

     Teachers and parents all think the book is a very good idea. It will teach students how to be a good person

in the online world. It will be a guide for teens using the Internet and keep students away from bad sites.

1. The report shows that _____ of the 3 375 students are playing online games too much.

A. 38%

B. most

C. many

D. a few

2. How does the textbook teach students?

A. With real examples.

B. With pictures.

C. With music.

D. With tapes.

3. Which of the following useful advice is NOT mentioned in the passage?

A. Read news.

B. Find information.

C. Make friends.

D. Watch films. 

4. What do teachers and parents think of the textbook?

A. It's a very good idea.

B. It's a foolish idea.

C. It keeps students looking at bad sites.

D. It can't teach students how to be good.

单项选择题