1.关系代词指代先行词在定语从句中作表语时只用that,但时常省略。
She is no longer the girl that she used to be. 她不再是过去那个女孩儿了。
2.以the way为先行词的限制性定语从句,通常以in which或that引导,但通常省略in which或 that。
The way (in which) he spoke to his classmates was unfriendly.他跟同学说话的方式并不友好。
3.以reason为先行词的限制性定语从句,如果先行词reason在定语从句中做状语,通常以why引导,但人们通常省略why。
That is the real reason (why) they left their hometown. 那是他们离开家乡的真正原因。
4.在there be 句型中,关系代词总是被省略。
There is a lady (who) wants to talk with you. 有一位女士想和你谈谈。
还有其他情况的省略,需要大家平时点滴积累。