在某工程双代号时标网络计划中，除以终点节点为完成节点的工作外_爱下问搜题

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问题单项选择题

在某工程双代号时标网络计划中，除以终点节点为完成节点的工作外，某工作箭线中的波形线的水平投影长度表示( )。

A．某工作的总时差
B．某工作与其紧前工作之间的时间间隔
C．某工作的持续时间
D．某工作与其紧后工作之间的时间间隔

答案

参考答案：D

完形填空

完形填空。

      Scientists think that there has been life on Earth for millions of years. However, we haven't found life
__1 _ other planets yet.
    Scientists have discovered many other galaxies in the universe. They are a long way away and their  _2_
has travelled for many years to reach us. Scientists have sent   _3  of spacecraft to look at other planets in
our solar system, and some spacecraft   _4_   beyond the solar system. However, no one   _5    discovered any life in space yet.

( )1. A. in
( )2. A. light
( )3. A. lot
( )4. A. have gone
( )5. A. have

B. on
B. lights
B. a lot
B. have been
B. has

C. to
C. sound
C. lots
C. have been to
C. have got

D. for
D. sounds
D. a lots
D. have gone to
D. has got

填空题

科研中假设的作用包括：（）、逻辑推导、发展理论。