1.一般过去时的句子中,其谓语动词使用过去式.
也就是说：过去式直接做（一般过去时态的）句子的谓语.
如：I read a book yesterday.
2.而过去分词不能单独做句子的谓语动词,它主要有以下用法：
1）用在be动词后,一起做被动句的谓语
如：A book was read by me yesteday.
2）用在助动词have/has/had之后,一起做（现在完成时/过去完成时的）句子的谓语
如：I have read many books so far.
3）做非谓语成分,如表语、定语、状语、补足语和独立成分等.
如：I want to buy a book (read by you yesterday).后置定语
