Помогите! 22.3 Составьте предложения...

22.3.

2 My younger sister can stay alone now, but she could not do it last year.

3 My best friend can play tennis now, but he(she) could not do it a month ago.

4 Your dog can open the door itself now, but it could not do it last week.

5 I can sing very well now, but I could not do it when I was a child.

6 He can cross the river now, but he could not do it when he was younger.

7 She can run very fast now, but she could not do it two years ago.