My friend Jack always had accidents. He did not1 attention to what he was doing or where he was going.

 A few months ago, 2car hit him while he was on his way home from school. The driver was tired,3 he did not see Jack. And Jack was talking on4 mobile phone and was riding in the middle of the road. The car hit him. He 5 his leg and was in hospital for over a month.

  Last week, he was not looking 6 he was going as usually. As a result, he fell into a hole 7the park. Some 8people in the park helped him climb out of the hole and then took him to hospital. 9 he did not break an arm or a leg this time. At the hospital, the 10 gave him some medicine and then he went home.

  After the two accidents, Jack changed a lot. Now he is very careful.

小兔数了____颗．

国务院常务会议通过的《校车安全管理条例》规定：载有学生的校车在高速公路上行驶的最高时速不得超过80公里，在其他道路上行驶的最高时速不得超过60公里…在冰雪、泥泞的道路上行驶最高时速不得超过20公里．清点乘车学生人数，帮助、指导学生安全落座、系好安全带…

请同学们利用已学过的物理知识，分析校车在冰雪、泥泞的道路上行驶时，要减小车速的原因及学生要系好安全带的目的．

使至塞上

王维

单车欲问边，属国过居延。

征蓬出汉塞，归雁入胡天。

大漠孤烟直，长河落日圆。

萧关逢候骑，都护在燕然。