House prices vary from place to place and are usually high ________ there are famous schools.
---Where did you come across our chemistry teacher ? --- It was in the supermarket ______I purchased mooncakes.
________ the Internet is of great help, I don’t think it’s a good idea to spend too much time on it.
—I’m really hungry now. That’s because you have left your lunch __________.
— How much do I owe you for this supper? — _________. It’s nothing.
When Marx was in London, he _______ read at the library for hours.