did和were.was的用法有什么不同
准确来说did和were.was 助动词do 和be动词的过去式。
I did homework yesterday. (did实意动词，意思做作业的做)
I didn't do homework yesterday. (did助动词， 无实际意义 表 过去式)
I was born in 2000. （was是系动词 be 的过去式）
Many famous people had dreams when they were young。（were是系动词 be 的过去式）
was 前面主语是单数，were前面主语是复数，
