定语从句讲解：先行词和关系词的区别：

　　1)Whoever spits in public will be punished here.(“Whoever”可以用“anyone who”代替)

　　2)The parents will use what they have to send their son to technical school. (“what”可以用“all that”代替)

　　但这两句句子已经不是定语从句了，是名词性从句。因为定语从句一定要有先行词，而名词性从句没有。将“Whoever”、“what”分别用“Anyone who”、“all that”代替后，才是定语从句，先行词分别是“Anyone”、“all”。

　　An invitation from her boss, ___came as a surprise.

　　A. it　B. that　C. which　D. he

　　答案C。

　　a选项it，使前后成为两个句子，中间无连词连接，语法错误;b项that，此为非限定性从句，不能用“that”修饰;c选项which，which在从句中做主语，用来代指前面的这件事;d选项he;前半句中是her boss，所以不正确。

　　2)The weather turned out to be very good, ___ was more than we could expect.

　　A. what　B. which　C. that　D. it

　　答案B

　　A选项不能用来引导定语从句，C选项只能引导限定性定语从句，而D选项习惯上并不适用。

　　3)It rained hard yesterday, ____ prevented me from going to the park.[2]

　　A. that　B. which　C. as　D. it

　　答案B