He works _____ in English, but he can ____ make progress.
-- 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.
I _______ riding my bike________ taking buses to school.
— Can you come and play football with me? —______. I have a lot of homework to do.