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.