9. Where does this conversation take place?

A. In the sitting room.　 B. At the airport　　 C.　 On the phone.

8. What can we learn from the conversation?

A. Jane goes to work by bike every day.

B. The man doesn’t want Jane to buy a car.

C. The woman wants the man to buy a new Benz.

听第七段材料，回答第9至第11题

7. What does the man most probably do?

A. A driver.　　 B. A teacher.　 C. A police man.

6. What did Tom buy yesterday?

A. A second-hand Ford.　 B. A new Benz. C. A new Toyota.

4. What does the woman suggest the man buy?

A. A purse.　 B. A dress.　 C. A pair of shoes.

3. Why did the man go to Shenzhen?

A. For sightseeing.　 B. To visit his friends　　 C. On business.

2. What can we learn from the conversation?

A. The man wrote a song yesterday.

B. The woman knows how to play the guitar.

C. The woman is a singer of a band.

1.　　　　 Where does the woman want to go?

A. The post office.　 B. The National Library.　 C. The People’s Hospital.

13．在验证机械能守恒定律的实验中，质量为m=1.00kg的重锤拖着纸带下落，在此过程中，打点计时器在纸带上打出一系列的点。在纸带上选取五个连续的点A、B、C、D和E，如图所示。其中O为重锤开始下落时记录的点，各点到O点的距离分别是31.4mm、49.0mm、70.5mm、95.9mm、124.8mm。当地重力加速度g=9.8m/s²。本实验所用电源的频率f=50Hz。(结果保留三位有数数字)

(1)打点计时器打下点B时，重锤下落的速度v_B=　　　　　　 m/s，打点计时器打下点D时，重锤下落的速度v_D=　　　　　　　 m/s。

(2)从打下点B到打下点D的过程中，重锤重力势能减小量重锤动能增加量△E_k=　　　　　　　 J。

(3)在误差允许范围内，通过比较　　　　　　　　　　　　　　　 就可以验证重锤下落过程中机械能守恒了。

(4)设重锤在下落过程中受到恒定不变的阻力F，则可根据本实验数据求得阻力F的表达式为　　　　　　　　　　　　　　　　 (用题中所给的字母m，g，s₁，s₂，f表示)。