If a bag is filled with books and pens, it must belong to someone ________ works hard．

A．which

B．/

C．whom

D．who

阅读短文，然后从方框中选出可以填入文中空白处的单词，并将其填入短文后相应题号的横线上。

　　People are often killed while crossing the road．Most of them are old people and children．Old people are often killed because they usually can't see or hear very 　　1　　．Children are often killed because they are 　　2　　．People should look and listen 　　3　　 they cross the road．

　　A car, truck or bus can't stop very quickly if a ear is 　　4　　 very fast．It will travel many metres before it stops．Pedestrians don't always know 　　5　　．They think a car can stop 　　6　　 away．The faster a car is travelling, the 　　7　　 it takes to stop．It's very 　　8　　 for a pedestrian to know how fast a car is travelling．

　　The only safe way to cross the road is to look at both ways, right and 　　9　　．The correct way to cross the road is to walk quickly when the traffic lights 　　10　　 green．It's not safe to run．

1．________　2．________　3．________　4．________　5．________

6．________　7．________　8．________　9．________　10．________