составьте предложения.Используя can и could.

2 My younger sister can stay alone now, but it could not do last year.
3 My best friend can play tennis now, but it could not do a month ago.
4 Your dog can open the door itself now, but it could not do last week.
5 I can sing very well now, but it could do when I was a child.
6 He can cross the river now, but it could do when he was younger.
7 She can run very fast now, but it could do two years ago.