英语语法翻译？

students who\that cheated in the exam
要看修饰的对象。that既可指人也可指物；who只能指人；which只能指物。
He is the man who/ that I saw yesterday.（who/that在从句中作宾语）
A friend who/ that helps you in time of need is a real friend . （who/that在从句中作主语）
一.只能用that作为定语从句的关系代词的情况 ：
1) 在不定代词,如：anything, nothing, everything, all, much, few, any, little等作先行词时,只用that.
All that is needed is a supply of oil.
2) 先行词有the only, the very, the just修饰时,只用that.
He is the very man that helped the girl out of the water .
3) 先行词为序数词(the last)、数词、形容词最高级时,只用that..
The first English book that I read was “The Prince and the Pauper” by Mark Twin .
4) 先行词既有人,又有物时.
He talked about the teachers and schools that he visited .
5)当主句是以who 或which 开始的特殊疑问句时,用that 以避免重复.
Who is the person that is standing at the gate .
二.不能用that的情况，而用which/who：
非限定性定语从句，逗号后面只能用which。
The sun heats the earth, which is very important to us.

关系代词前有介词时.
This is the hotel in which you will stay.
如有两个定语从句,其中一句的关系代词是that,另一句宜于用which.
Let me show you the novel that I borrowed from the liberary which was newly open to us.

以上区别请参考