诵读下列例句并感知画线部分的共性
1. There were deep cracks that/which appeared in the well walls.
2.Two thirds of the people who lived there were dead orinjured.
3.The number of people_ who were killed or badly injured in the quake was more than 400,000.
4. Soon after the quakes, the anmy sent 150,000 soldiers to Tangshan to dig out those who were trapped and to bury the dead.
5. Workers built shelters for survivors whose homes had been destroyed.
6.A doctor with whom James used to work died in the 2016 earthquake in Ecuador.
7. The boy whose father is a teacher is a new classmateof mine.
8. China is a country that/which has a long history.

1.第2、3、4句中的定语从句使用了关系代词 who，在定语从句中作主语。
2.第1、8句中的定语从句使用了关系代词 which/that，在定语从句中作主语。
3.第6句中的定语从句使用了关系代词 whom，在定语从句中作宾语。
关系代词who/whom常用来指代人;关系代词that/which常用来指代物;关系代词that既可以指人也可以指物。
4.第5、7句中的定语从句使用了关系代词whose，在定语从句中作定语，它既可以指人也可以指物。