—How many lessons do you usually have a day? —Six lessons a day. And each of them _____45 minutes.
The development of the city's industry __________ its environment pollution.
He has worked __________ the maths problem for nearly an hour but he simply can't work it __________.
The energy Jenny Bowen has devoted in the past ten years __________ the orphans has been considered __________ of great help.
The __________ on his face told me that he was angry.
Lucy asked for a separate room so that she could avoid __________ with Tom alone.