问题 单项选择题

公路桥涵设计的作用(或荷载)分类,以下______项正确

A.恒载、车辆荷载及其影响力、其他荷载和外力
B.永久作用、基本可变作用、偶然作用
C.永久作用、可变作用、偶然作用
D.恒载、汽车荷载、风力、地震力作用

答案

参考答案:C

解析:
公路桥涵设计采用的作用分为永久作用、可变作用和偶然作用三类。公路桥涵设计时,对不同的作用采用不同的代表值。永久作用应采用标准值作为代表值。可变作用应根据不同的极限状态分别采用标准值、频遇值或准永久值作为其代表值。承载能力极限状态设计及按弹性阶段计算结构强度时应采用标准值作为可变作用的代表值。正常使用极限状态按短期效应(频遇)组合设计时,应采用频遇值作为可变作用的代表值;按长期效应(准永久)组合设计时,应采用准永久值作为可变作用的代表值。偶然作用取其标准值作为代表值。作用的设计值规定为作用的标准值乘以相应的作用分项系数。

阅读理解

阅读理解。

     Never try to work when you are very hungry. If youwant to do your homeworkright after school, you maywant to eat something before getting to work. (1) Alwaysdo your homework beforeyou get too tired. Don't wait till very late in theevening, or your homework will seem muchharder than it really is.  

     Break your time into a few parts if youhave more than an hour' s work, and giveyourself (2)a break after an hour. On the otherhand, (3) you should be able to work at leasthalf an hour at a time without stopping.      

     Don't put it off until the last minute. If youput off doing your homework, you will have iton your mind, and you won't enjoy your freetime so much. If you put it off until the end of aweek or until right before a test, you will havetoo much to do. A little each night, enough tokeep up with what is happening each day inschool, will take the fear out of tests and keep you on top of it.

1.Always do your homework before you get too  tired.  (改为同义句 )  

________ you get too tired, you should _______  doing your homework.

2.What's the meaning of "a break"?  

A. a sleep                  

B. an idea  

C. a rest                    

D. a moment

3.把(3)处句子翻译成汉语。

4. Which sentence is NOT true from this passage?    

A. Don't put off doing your homework.    

B. Don't wait till very late in the evening to do your homework.    

C. Eat something to keep yourself not hungry.    

D. Have a short break after working for more  than two hours.

5.选取文中的两个单词填空。  

(1) He has a good _______ to beat his dog.  

(2)1f you____  the rule, the teacher will  call your parents.

单项选择题