现在一般时与现在完成时
1) I come from Shanghai(上海人）
I have come from Shanghai（从上海来）
2) You read very well.(强调能力）
You‘ve read very well.（强调一次刚完成的动作）
3) I forget.(一时想不起来了）
I have forgotten.（仍没想起来,可能已回忆起来了）
4) The book is written in simple English.(表状态）
The book has been written in simple English.（表动态,已用英语写成）
5) Every time I see him,he‘s been reading.（两个动作不可能同时进行）Every time I have seen him,he‘s been reading.(强调两个动作同时进行）
6) He is gone.(强调状态）He has gone （强调动作和时间）
7) He won‘t come till the play begins.(演出开始时）
He won‘t come till the play has begun.（戏已开始）
8) After I leave school,I‘ll go to college.（两个动作紧密相接）
After I have left school,I‘ll go to college.（强调毕业后,两个动作可能有间隔）
9) It is a long time since I saw you last.It‘s been a long time since I saw you last.(这两句话一样,后一句是美国英语）
10) Where are you?(在哪）Where have you been?(去了哪）
请仔细品位一下 关键看自己理解
