联系代词who, which, that 的考题：
　　I know the girl. The girl works in IBM.
　　I know the girl who / that works in IBM.
　　The old man is a famous artist. We visited the old man yesterday.
　　The old man who /that we visited yesterday is a famous artist.
　　The laptop is made by DELL. I bought the laptop last week.
　　The laptop which / that I bought last week is made by DELL.
　　先行先试词为接下来原因，问题代词务必用that:
　　1.优先词被描述词至一级淡化：
　　He is the hardest-working student that I have ever taught.
　　2.排头兵词被序数词表达：
　　He is the first man that finished the work on time.
　　3.排头兵词被only, just, the same, next等词淡化：
　　This is the only dictionary that I have at hand.
　　4.先词其实质就为波动代词：
　　Is there anything that I can do for you?
　　5.为先词中既收录人又收录物：
　　We know nothing about the doctors and the hospitals that you are talking about.
　　6.确认使用方法中，优先词是动物界的是
　　We have to protect whales and sharks that are being threatened by death.