1) The scientist has already written his article.
2) They discussed their problems last night.
3) Mike has just visited his grandmother.
4) The boys found a ball yesterday.
5) Andrew's hamster hasn't eaten his food yet.
6) The opera singer changed her dress during the last break.
7) I have just read this modern magazine.
8) Ann saw this fantastic film last Monday.
9) Have you ever visited London Tower?