Choose the correct forms.
1 'How long have you been working / are you working on this project?' 'We have been working / are working on this project since September, but we might not / must not finish it in time."
2 'I have seen / have been seeing Leonardo's Last Supper twice.' 'When did you last see / have you last seen it ?'
3 I was sitting / sat on top of a hill when I heard / was hearing the sound of dogs and horses approaching.
4 Francis was sure he has met / had met the man before.
5 He wanted to know / know what had provoked/ provoked my bad temper.
6 I encouraged her to talk / talk about the episode but she decided to keep / keeping it to herself.
7 So she didn't call you again? That's a pity because I might have helped / may help her then.
8 I can't help feeling / to feel nervous before an exam.
9 Believe or not, once Tim would break / broke his leg near this lake.
10 It was / has been a surprise. I haven't / hadn't expected to win anything at that moment.
11 What was he thinking/ had he thought about when he painted / was painting the picture?
12 'Where is/was Don?' 'Check the kitchen. He can pos could be there.​