所谓定语从句,就是有个句子要做定语,只需要把作定语的句子改成像形容词一样修饰名词的短语就好啦（可以当做形容词,就是这个形容词比较长）
举例：
i have a pen.
i bought the pen yesterday.
=i have a pen which/that was bought yesterday.
我的钢笔是昨天买的.（“昨天买的”当做定语,修饰钢笔.）
i have a sister.
my sister's name is Lily.
=i have a sister whose name is Lily.
我的姐姐叫莉莉.（“名字叫莉莉”做“姐姐”的定语.）
以此类推~
其实定语从句挺简单的了,但要分清that,which,what,who等的用法限制就好了~
