I went to the USA.一般过去时 I didn't go to the USA.一般过去时否定句 Did you go to the USA?一般过去时疑问句 I did my homework.一般过去时 Ididn't do my homework.一般过去时否定句 Did you do your homework?一般过去时疑问句 I was doing my homework.过去进行时 I wasn't doing my homework 过去进行时否定句 Were you doing your homework?过去进行时疑问句
