做好实验室的本质安全就是要采用更安全的仪器设备和实验装置、规范设备管理、规范人员操作行为，从源头上避免事故。

Cats are creatures of habit．They like to go to sleep ab...

单项选择题Cats are creatures of habit．They like to go to sleep about the same time every day and for a certain length of time．They seem to have a natural clock inside them that tells them when to sleep．
Cats increase their regular sleep with occasional cat naps (打盹)．Some experts feel that humans could also benefit from this habit．Cat naps help to build up energy in the body．They are also a good way to get rid of trouble! Since cats have the same moods(情绪) as humans, some experts believe that people can improve their moods．People might become happier．
A number of famous people have copied cats by taking cat naps during the day．The naps would usually last from 15 to 30 minutes．
Winston Churchill took cat naps．So did Presidents Harry Truman, John F．Kennedy and Lyndon B．Johnson．These famous men were known for their energy．They were also able to work long hours, often into the night．Napping was their secret．
Perhaps more people learn from cats and take naps to feel better and live longer!
Taking cat naps_______．

超声法检测混凝土结构内部缺陷，是否存在缺陷的判据不包括（)A.声速B.接受波幅C.接受频率D.发射波幅

单项选择题超声法检测混凝土结构内部缺陷，是否存在缺陷的判据不包括（)

Sometimes I feel that being the mother of three small c...

单项选择题Sometimes I feel that being the mother of three small children is like operating a large circus(马戏团)． 21 afternoon last week, my three sons playing peacefully in the back yard ( 院子), 22 the ball from one to another．I jumped at the chance to talk to one of my friends 23 the phone, but before I 24 to the phone, I could tell the boys had begun to quarrel with each other about something．I rushed out to 25 peace,but before I got there Charles had 26 a rock at Mark,and hit him in the eye．By the time I got to the back yard,they had begun to 27 about this．Even David,the oldest boy,who won' t usually fight with anybody about 28 ,was involved(卷入) First,! 29 them stop fighting, and then ! examined Mark' s eye．I decided that it wasn' t going to develop into a black eye, but I felt that they should 30 at least a little for 31 they had done．"I' m going to 32 to your father about this when he comes home tonight,"I said．"He and I will think of how to punish you．"Things were 33 quiet after that for about half an hour, and then Charles 34 a glass in the kitchen,and at almost the same 35 ,Mark fell out of the apple tree．
第（33）题答案