作业帮
present perfect;：indefinite past
past perfect tense
The future Perfect Continuous Tense 用法 .过去完成进行时 the past per
present perfect tense,past perfect tense
造句用 past simple and present perfect
present perfect,simple past,请帮忙答题.
用present perfect tense ,simple past tense ,
past continuous/present continuous/present perfect continuou
past perfect vs.simple past.Choose the correct verb form.
请问present/past perfect tense 跟present/past perf
use the past simple and the past perfect simple
Simple past和past perfect那个较早发生