People say that young Chinese students’ eyesight keeps dropping _________ because of both too much homework and poor learning conditions

In my opinion, we need to begin ______ we stopped yesterday to ensure we won’t miss anything.

My son is _____ to be seen. Where has he gone? — I think he _____ in the building.

I wonder ___________.—-It’s next to the hospital.

She was surprised to find the fridge empty；the children _____ everything !