关系代词who.which.that什么时候可以省略?如题

Question

关系代词who.which.that什么时候可以省略?
如题

Answer 1

如果修饰事物,用关系代词which 和that,作宾语时可省略.作介词宾语时,如果介词位于关系代词之前,则用which (不能省) ,而不用that（关系代词that既能代人,又能代物）.whose也可用来指物（此时可用of which来代替）,在定语从句中作定语.
如：
①Don’t buy tomatoes that/ which are green.
不要买颜色还是青的西红柿.
( that/ which 在定语从句中作主语,不能省)
②The fish (that/ which) they sell are not fresh.
他们卖的鱼不新鲜.
（ that/ which 在定语从句中作宾语,可以省）
③The classroom whose door is broken will soon be repaired.
= The classroom the door of which is broken will soon be repaired.
门坏了的那个教室将很快修理.
④The tool with which he is working is called a saw.
=The tool (that/ which) he is working is called a saw.
他干活用的那个工具叫叫锯.
（介词with位于关系代词之前,须用which,不能省,也不能用that）.
谢谢～