Измените предложения,поставив глагол-сказуемое в указанное в скобках время.Употребите соответствующее обстоятельство времени.
1.Mother is watching TV.(present simple,past continuous,past simple)
2.Mary studied English last year. (present continuous,future simple)
3.He has already done the exercise.(past continuous,past simple,present simple)
4.The students are in the room.(past Simple,future simple,past continuous).