11. The last time I really enjoyed myself was at your birthday party.

=>I haven't really enjoyed myself for at your birthday party

12. It's nearly 20 years since my father saw his brother.

=> My father hasn't seen his brother for nearly 20 years.

13.Tom last went to Scotland a year ago.

=> Tom hasn't gone to Scotland for a year

14.When did you last ride a bike?

=> How long have you ridden a bike?

15.The last time I went swimming was when I was in France.

=> I last I went swimming when I was in France.

=>I haven't gone swimming since I was in France.

16.You haven't tidied up this room for few weeks.

=> It's few weeks since I last tidied up this room

17. He last kept in touch with me three weeks ago.

=> He hasn't kept in touch with me for three weeks

18. Mr John hasn't visited France since 1990.

=> Mr John last visited France in 1990

20. It last rained three weeks ago.

=> It is three weeks since it last rained.

21.I haven't eaten this kind of food before.

=> This is the first time I have eaten this kind of food.

`11to` I haven't really enjoyed myself at your birthday party.

`12to` My father hasn't seen his brother for nearly 20 years.

`13to` Tom hasn't gone to Scotland for a year.

`14to` How long have you ridden a bike?

`15to` I haven't gone swimming since I was in France.

`16to` It's few weeks since I last tidied up this room.

`17to` He hasn't kept in touch with me for three weeks.

`18to` Mr. John last visited France in 1990

`20to` It is three weeks since it last rained.

`21to` This is the first time I have eaten this kind of food.