汽车驾驶员手册规定：具有良好刹车的汽车，以v1=80 km/h的速度行驶时，应在x1=56 m的距离内被刹住；以v2=48 km/h的速度行驶时，应在x2=24 m距离内被刹住。假设两种情况下刹车后的加速度大小相同，驾驶员在这两种情况下的反应时间相同，则反应时间约为[ ]
A．0.5 s
B．0.7 s
C．0.9 s
D．1.2 s
答案：B
| 完形填空。 I was tired. I had been studying English for 8 years, but my spoken English was still terrible. I went to English school every night. I read different textbooks and learned the grammar rules 1 them every day. But during the eight years, I hadn't got any 2 at all! Being tired of school, I searched (搜索) the Internet for "Learn English" one night. Then I found a 3 English learning system (系统). Seven days later I started using the system to learn English. My life 4 from then on. I used the system every day. I was 5 to find that learning English in this way was so easy and interesting. No boring grammar rules. The articles were interesting and the stories were very funny. Then something amazing happened. One day I 6 an American man named James in a coffee shop. Without thinking, I started to 7 him. My English words came out automatically (无意识地). It was hard for me to believe it. I could speak English so easily. I didn't feel any 8 or worry. James understood my ideas and feelings. We talked for two hours without 9 . Then we exchanged e-mails and Skype IDs. We decided to talk to each other on the Internet every week. My English has 10 greatly now. I think there are many ways of learning English for us to use. You should stop using a way that doesn't work and find out what is helpful to you. | ||||
|