"since"dùng với một mốc thời gian trong quá khứ và có thể vẫn tiếp tục ở hiện tại.
VD: since Wednesday, since last summer, since 1999...
"for"dùng với một khoảng thời gian trong quá khứ.
VD: for six years, for a month, for two days,...
1.She has been sick since Wednesday.
2.John has worked in that firm for six years.
3.He has been in the hospital for almost a month.
4.They haven't sent him any money since last summer.
5.She has not eaten anything for two days.
6.They have been friends since high school.
7.They have lived with her parents since they were married.
8.We've lived here since 1999.
9.I haven't seen Linh since my birthday party.
10.That building has been there since the 19th century.
11.My brother works for a company called FPT. He has worked for them since he graduated from university.
12.My sister has been a student for two years.
13.She's been away for five days.
14.We've already waited for a year.
15.I haven't seen him since he left home.
16.It has been raining since lunch time.
17.My boss will go away for the next ten days.
18.I'm staying in England for a year.
19.She has lived in London since 1985.
20. Please hurry up! We have been waiting for an hour.
