1 I have been trying to open this box for the last forty minutes but in vain.
2 It has snowed : the garden is covered with snow.
3 Who has broken the window?
4 Have you been smoking?
5 It's the best book I have ever read.
6 I have been listening to you for the past half an hour, but I can't understand what you are speaking about.
7 How long has your aunt been ill?
8 The school has been closed for two months.
9 Hey! Somebody has drunk my coffee! My cup was full.
10 I don't think I have ever seen her looking so upset before.
11 I have been sitting here in the park for an hour, and I have met three friends of mine.
12 How much money have you saved for the holidays?
13 I have been waiting for you since two o'clock.
14 She has taken guitar lessons this year. .
15 Last season our team didn't win many games, but this season we have lost only one so far.