问题 单项选择题

在某工程双代号网络计划中,如果以关键节点为完成节点的工作有3项,则该3项工作()。

A.自由时差相等

B.总时差相等

C.全部为关键工作

D.至少有一项为关键工作

答案

参考答案:D

解析:工作自由时差=节点最早时间-该工作最早完成时间, 工作总时差=节点的最迟时间-该工作的最早完成时间。 但3项工作的最早完成时间不一定相等,故选项A、B都不正确。

阅读理解

Every student has tests when they are at school. But have you ever been so worried about the tests that you can’t fall asleep at night? Have ever felt sick or had a headache during a test?    71  . This worry in your mind can make your body feel bad. You may feel angry, frustrated, scared, or afraid --- which can give you a stomachache or a headache.

   72  . Good or normal stress might happen when you are called to answer a question in class or when you have to give a speech. This kind of stress can help you to get things better done.    73   .

But bad stress can happen if the stressful feelings keep going over a long time. You may not feel well if your parents are fighting, if a family member is ill, if you are having problems at school, or if you are going through anything else that makes you upset every day.    74  .

    75   . That means making good decision about how to spend your time. If you are only dealing with school stuff and have no time to play, you can get stressed. Make sure you keep your SELF in mind: Sleep, Exercise, Leisure and Food. If you take care of yourself and get enough sleep and food, and if you exercise and leave time for fun stuff, you will probably be less stressed out!

A.However, there are two different kinds of stress.

B.Can you tell a kind of stress from another one?

C.The best way to keep stress away is to have a balanced life.

D.That kind of stress isn’t going to help you, and it can actually make you sick.E. Since bad stress is harmful for us, you’d better try to change it into good stress.

F. If so, then you know what stress is. Stress is what you feel when you are worried or uncomfortable about something.

G. For example,you may do a better job on your test if the stress pushes you to prepare well before the test.

单项选择题