Раскрыть скобки и употребить одно из времен continuous. i (to talk) over the telephone, when she entered the room. they (to watch) tv while their mother (to cook) dinner. where is the teacher? – he (to ask) questions now. the engineers (to test) a new machine the whole day tomorrow.listen! someone (to knock) at the door.

I was talking over the telephone, when she entered the room.
They were watching TV while their mother was cooking dinner.
Where is the teacher? – He is being asked questions now.
The engineers will be testing a new machine the whole day tomorrow.
Listen! Someone is knocking at the door.