Scientists say it may be five or ten years___________ it is possible to test this medicine on human patients.
--- Where did you get to know him? --- I think it was in the factory______ I worked ten years ago.
—Why does the lake smell terrible? —Because large quantities of water .
—Hi, Tom, why are you looking so tired? —I'm tried. Because I ______ the living room all day.
__________ is troubling me is __________ I don’t understand __________ he said.
______________________, I would have given you his address.