We won’t go back home ___ the rain stops. We now have to stay in the classroom.
They found difficult to finish the work in such a short time.
--The factory wants to make more cars with _____money. --I think it's impossible.
-- You look_____. Why?--I lost my ID card.
I met Li Lei_____ hospital last Sunday. He was ill_____ hospital then.
The earth will become worse and worse ________ we do something to stop her from being polluted.