Present Perfect/Perfect Continuous.
1.I...(to try) to open this box for the last forty minutes.
2.It...(to snow) : the garden is covered with snow.
3.Who...(to break) the window?
4.Have you...(to smoke)! I can smell tobacco on your clothes.
5.It's the best book I ... (ever to read).
6.I...(to listen) to you for the past half an hour, but I can't understand what you are speaking about.
7.How long has your aunt...(to be ill)?
8.The shool...(to be closed) for two months.
9.Hey! Somebody...(to drink) my coffee! My cup was full.
10.I don't think I...(ever to see) her looking so upset before.
11.I...(to sit) here in the park for an hour, and I...(to meet) three friends of mine.
12.How much money have you...(to save) for the holidays?