六年级英语手抄报关于过去式

The past tense (abbreviated pst) is a verb tense expressing action,activity,state of being in the past of the current moment (in an absolute tense system),or prior to some other event,whether that is past,present,or future (in a relative tense system).
In English,there are two distinct types of past tense:
Preterite (or simple past)
Present perfect (see perfect aspect)
Each of these may also be found in the progressive (continuous) aspect.

过去式的变法，在什么情况下游过去式，过去式应当注意些什么。