Поставьте глагол в нужной форме, применив правило согласования времен: 1)he said we (may) keep the books as long as we (to like). 2)we thought that he not (to be able) to make his work in time and therefore (to offer) to help her. 3)when i came they (to tell) me that he (to leave) half an hour before. 4)it was soon clear to the teacher that the control work (to be) a difficult one.