难点1：关系副词where和when引导的定语从句的转化：
难点2：当先行词为reason，且在定语从句中做状语时，定语从句的4种引导方式：why/for which/that/不填。以下四句意思是一样的：
难点3：当先行词为way，且在从句中做状语时，定语从句的三种引导方式： in which / that /不填。以下三句意思是一样的：
说明：
1)关系副词除了常见的where和when外，还有why（why=for which），但切记没有how，没有the way how he explain the sentence to us is quite simple这一说。
难点4：当先行词是time时，若time表示“次数”，用that引导定语从句，that可省略； 若time表示“一段时间”，则用关系副词when或介词at/during which引导定语从句。
This is the second time (that) the President has visited the country.（一般that不省略，有时被当成一个句型记忆，从句后一般用完成时）
I could hardly remember how many times (that) I"ve failed.
Every time (that) I saw her, I said hello.（一般that省略，表述更简洁）
难点5：whose引导的定语从句及其转换
Whose引导定语从句，先行词可以是人也可以是物，whose在从句中做定语。Whose+名词的结构常可以用the+名词+of which 或 of which + the+名词的结构替换，意思相同。
The house whose roof was damaged has now been repaired.
=The house the roof of which was damaged has now been repaired.
=The house, of which the roof was damaged, has now been repaired.
难点6：两个以上的简单句组成一个句子时，必须用关联词来连接两个句子，而不能用代词。
改错中经常会出现：
1）This is our monitor, without him, we couldn’t win the game. （此句中人称代词him必须改为引导词whom）
2） Can you see the tall building, in front of it there is a large playground? (此句中的代词it必须改为引导词which)
难点7：which引导的非限定性定语从句，除在从句中做主语、宾语或表语外，还可以做定语，起到限定词的作用，但其前面必须有介词。
He lost his temper, at which point I decided to go home.
His son insisted on joining the army, in which case he had to give in.
难点8：One of +复数名词位于关系代词前作先行词时，从句中的动词通常用复数，但当one前有the only, the very等修饰时，从句的谓语动词要用单数。例如：
He is one of the students who have made great progress.
Mr Wang is the only one of my friends who has been invited to have dinner with us.
