★一般现在时:

often, usually, always, sometimes, never, seldom, every week/day/year/month..., once a week, on Sundays

★一般过去时：

ago, yesterday, the day before yesterday, last week/year/night/month..., in 1989, just now, at the age of five, one day, ago, long ago, once upon a time, then(那时), on that day,

★现在进行时：

now, at this time, these days, Listen! Look! at this moment/time

★过去进行时：

at this time yesterday，at that time或"when + 一般过去时从句", at 1:00 last night

★现在完成时：

recently, recent years, these days/years, lately, since, for + 时段, in the past few years, ever since, in the last five months, up to now, since then, so far, ever, never, yet, lately, once, twice, three/four times..., already, before, just.

★过去完成时：

before, by the end of last year/term/month...

★一般将来时：

tomorrow, next day/week/month/year..., soon, in a few minutes, by..., the day after tomorrow, in the future

★过去将来时：

the next day/morning/year...,

the following month/week...