英语中last表示上一个，所以

往往是一般过去时的标志。

例如

The teacher as well as the students went to the Great Wall last year.

What did you do last Sunday

I can remember the last time when I was punished by the teacher.

此外last还可以作动词，意思是持续，后面加段时间。

The big fire lasted four hours.

The meeting has lasted two hours.

last表示过去。比如last month上个月。

last表示的是过去的意思。

last表过去，What did you do last Monday