问题 选择题

天文观测表明,几乎所有的恒星(或星系)都在以各自的速度背离我们而运动.离我们越远的星体,背离我们的运动速度(被称为退行速度)越大.也就是说,宇宙在不断的膨胀,不同的星体的退行速度V与它们同我们的距离r成正比,即:v=Hr.公式中H为一个常量,称哈勃常数,已由天文观测者测定.为了理解上述现象,有人认为,“宇宙是在一个火球的爆炸中形成的.假设大爆炸后各星体以不同的速度,向外均匀运动,并设想我们就在爆炸中心,则速度越大的星体离我们越远,“这假设与上述天文观测一致.试确定哈勃常数H的单位(  )

A.s

B.m

C.m/s2

D.s-1

答案

因为v=Hr,则H=

v
r
,则哈勃常数的单位为
m/s
m
=s-1
.故D正确,A、B、C错误.

故选D.

完形填空

第一部分 完形填空(共20小题;每小题2分,满分40分)

完形填空(1) 阅读下面短文,掌握其大意,然后从1~10各题所给的A、B、C和D项中,选出最佳选项,并在答题卷上将该项涂黑。

A bar manager was so sure that he himself was the strongest man around      1             he offered a standing $ 1,000 bet that no one could beat him.

The  2          was that the landlord would squeeze a lemon until all the      3           ran out into a beer glass, then hand the lemon to the customer. Anyone who could squeeze even one more  4       out of the lemon would win the money.

0ver the years many people had tried this, truck drivers, weightlifters, karate masters, and   5         had failed. Then one day a little fellow with heavy black rimmed glasses came into the bar and asked if he  6           try the challenge.

After the laughter had quieted down, the landlord said that it was only        7       that the man be given a chance at the bet, so he picked up a lemon and started squeezing.  8          he had done he handed the  9             to the little man who promptly squeezed out 4 more drops of juice onto the bar!

Everyone looked on in amazement as the landlord handed over the prize and asked “What do you do  10      a living that has given you such strength? Are you a lumberjack, weightlifter?” “No.” the man replied, “I work for the IRS(国税局).”

1. A. that                      B. there                        C. therefore          D. since

2. A. fact                      B. trap                         C. challenge                  D. match

3. A. flesh                           B. juice                C. seeds                     D. peel

4. A. water                   B. lemon                    C. beer glass         D. drop

5. A. none                           B. neither                     C. either                    D. all

6. A. /                         B. could                       C. had to                    D. ought to

7. A. then                           B. likely                    C. fair                       D. chance

8. A. Once                   B. Right                      C. Immediately    D. In case

9. A. container                     B. money                     C. remains                    D. other

10. A. with                          B. for                          C. on                           D. in

单项选择题 案例分析题