阅读下面的短文，掌握其大意，然后从短文后各题所给的A、B、C、D四个选项中选出可以填入相应空白处的最佳答案。

    Every day some people are killed while they are crossing the roads. 1 of these people are old people and children.Old people are often killed because they can't see or hear very well.Children are killed because they are not 2 .They forget to look and listen before they 3 the roads.

    A car or a bus can't stop quickly.If a car is going very fast, it will travel many meters before it stops.Some people don't always understand this.They think a car can stop in a few meters.It is difficult to 4 how fast a car is moving.The only way to cross the roads safely is to look both ways, right and left.Then if the roads are 5 , you can cross them.

浙江省首个股份合作农场于2013年1月21日在仙居县落成，该农场以村民土地入股方式，配合“现代企业制度”管理，形成农业产业化。这一农场建立的意义在于（   ）

①完善农村的经营体制，提高资源利用率

②壮大了集体经济，有利于农业规模化经营 

③促进混合所有制经济在农村进一步发展

④扩大个体经济规模，促进农民就业与增收

看图填写方位词。

It' s time ____ go to bed.

给滑块一初速度v₀，使它沿与水平方向夹角为30度的光滑斜面向上做匀减速运动，当滑块速度大小减为 $\frac{v_0}{2}$ 时，所用时间可能是（   ）