高中阶段常见的使用现在完成时的标志单词词组

1、often,sometimes,ever,never,twice,on several occasion等：
Have you ever been to Beijing?
I have never heard Bunny say anything against her.
I have used this pen only three times.It is still good.
George has met that gentleman on several occasions.
2、现在完成时还往往可以同包括现在时间在内的时间状语连用
如now,up to these few days/weeks/months/years,this morning/week/month/year,just,today,up to present,so far等：
Peter has written six papers so far.
Man has now learned to release energy from the nucleus of the atom.
There has been too much rain in San Francisco this year.
The friendly relations and cooperation between our two countries have been enhanced in the past few years.
Up to the present everything has been successful.

for
例句：I‘ve been learning English for 9 years.

since
例句：I’ve been learning English since I was in grade 1.

yet
例句：I haven‘t decided yet.

already
例句：I hav...