Open the brackets using Present Perfect Continuous.
1) He (to try) to solve this problem for several months now but he hasn't found a solution yet.
2) He (to teach) at school for twenty years.
3) Mr. Smith (to work) in his room since early morning.
4) The children (to sleep) for 5 years.
He has been trying
He has been teaching
Mr. Smith has been working
have been sleeping
Объяснение:
незаконченное Действие, которое продолжается с до сих пор на протяжении времини