* Sửa đề câu `2` : Mary has played the piano for 4 years.
`1.`We haven't gone to London for two years.
`2.`Mary started playing the piano 4 years ago.
`3.`It's over a year since I last went to see them.
`4.`This is the first time she has been to the ballet dancing.
`5.`I have learnt English for five years.
`6.`The last time she went out with him was 5 months ago.
`7.`When did you buy the house ?
`8.`I last saw Tom when he moved to London.
`9.`I haven't visited Da Lat for 10 years.
`10.`We have worked here for three years.
`11.`Mr. Brown has had this car for five years.
`12.`I have studied English since I was 10 years old.
`13.`How long have you collected stamps ?
`14.`We haven't gone to the cinema for a long time.
`15.`I haven't gone swimming since 2001.
* Cấu trúc :
`a)` S + last + V2/ed + time + ago
`=`S + have/has not + Vpp + since/for + time
`=`It's + time + since + S last + V2/ed
`=`The last time + S + V2/ed + was + time + ago
`b)` S + have/has never + Vpp + before
`=`This is the first time + S + have/has + Vpp
`c)` S + began/started + Ving/ to V + time
`=`S + have/has + Vpp + since/for + time
`d)` When + did + S + V ?
`=`How long is it since + S + V2/ed ?
`=`How long + have/has + S + Vpp ?