Вопрос по английскому языку:

Find and correct the mistakes in the sentences. There is one mistake in each sentence.
1 The students haven’t seen all morning. I’ve no idea where they are.


2 The exams were corrected for our teacher. I think they took her a long time!


3 The classroom is been painted at the moment, so we have to work in the main hall.


4 The question can’t have answered. It’s much too difficult!


5 The 3D film was been seen by thousands of people on its opening night.