英语一般过去时再什么情况下用did/什么情况下用were /was/

Question

谁能讲明白些
天啊，你们说的我不明白，拜托讲明白些！`举例子好吗，详细一点，我很笨！```谢谢

Answer 1

1.谓语是be的情况下用were、was:

I am a student in XX university 我是XX大学的学生（现在时态）；I was a student in XX university 我曾经是XX大学的学生（过去时态）

2.谓语是其他动词的否定句情况下用did：

I study in XX university; I did not study in XX university.

3.谓语是其他动词的强调句情况下用did：

I do understand it 我确实明白了；I did understand it 我过去确实明白了。

Answer 2

当谓语是其他动词的情况下用did;当谓语是be的情况下用were、was;

Answer 3

就像 I was ill yestoday.
she did nothing yestoday.