题目

（9）某同学在做“利用单摆测重力加速度”的实验中，先测得摆线长为101.00cm，摆球直径为2.00cm，然后用秒表记录了单摆振动50次所用的时间为101.5 s。则： （1）他测得的重力加速度g =           m/s2.（计算结果取三位有效数字）(2) 他测得的g值偏小，可能原因是：              A．测摆线长时摆线拉得过紧。B．摆线上端未牢固地系于悬点，振动中出现松动，使摆线长度增加了。C．开始计时时，秒表过迟按下。D．实验中误将49次全振动计为5030、There is an old saying （谚语）: Early to bed, early to rise, makes a man healthy, wealthy and wise （富有而有智慧）．It means that we should go to bed early and get up early the next morning．By doing this, we will be in good health．And we’ll also be rich and clever． It’s true that our bodies need to have enough sleep to be healthy．Children should have a ten-hour sleep every night．Those who do not have enough sleep can’t do their work very well．They will not be clever and they may not get wealthy in the future． The body needs exercise too．Walking, running, jumping, riding bikes And playing games are all exercise．Exercise helps to keep the body strong And fit．It also helps the blood （血液） to move around inside the body．The head needs blood too．So exercise helps people think better． 1．What does the underlined word “rise” mean?     A．To do exercise．     B．To get up．      C．To stand up．  D．To put up． 2．If children don’t sleep for 10 hours every night, they may _____．     A．not be late for school                    B．become wise      C．do badly in their work                  D．become rich 3．A person needs exercise because _____．     A．it makes him healthy                     B．he has lots of work to do      C．he is strong                          D．he does exercise 4．Which of the following is NOT true? A．Exercise is good for people． B．It’s good for you to get up early and go to bed early． C．If you have enough blood, you will be wise． D．A student should have 10 hours’ sleep every night． 5．What’s the meaning of “Early to bed, early to rise’? A．The sun rises in the morning and sets （落下） in the evening． B．You should get up early and go to bed late． C．The sun rises early and sets late． D．You should get up early and go to bed early．