Do you want to work _____ us as a reporter?[ ]

I rang you at about ten o’clock, but there was no reply. – Oh, that was probably ________ I was seeing the doctor.

Now the air in our city is ________ than it used to be．Something must be done to stop it．

Today some newly-produced mobile phones can take pictures _____ a camera. [ ]

I think Zhuhai is one of _________ most beautiful cities in China and I’ll come for _________ second time.