完成had done have/has done will have done
标志词：1）by+ +过去时间：by the time…（在…时之前）, by the end of …（在… 结束/末之前）,by
then（截止到那时）;
2）up to/till（直到）+ 过
去时间：.up till then （直到那时）等
3）whe n, before, after, as soon as, till/ un til引导的有先后
的两个动作
4）由told/said/asked
等引导的宾语从句中
标志词：（已经，
标志
词：
by+将来
最近）already, 时间：by the just, yet, times +sb before, do/does
rece ntly, sth ,…will have still, done; by the end lately, of n ext rece ntly, in week/m on th/
the last few year 等
days ；
（次数）ever,
n ever, once ，
twice, several
times, how many
times ，how
long
（今天，这周/