They always communicated with each other on the Internet, but they never met him _____________.

There was thick haze（雾霾）in our city this year．What do you think of it—I think ________ cars we drive，____pollution our city will have．

We came to a house ________stood a tall tree

Our school _________ be an old shoe factory, now we ___________studying here. It is a good place to study.

I only intended to be there for a few days, but Iended up staying for a whole month