You’d better look up the new word in a dictionary _____ you don’t know it ?

She likes eggs, meat __________ milk, but I don't like meat, milk __________ eggs.

—I’m afraid that I can’t do it.—Oh, you should believe in yourself. You won’t know what you can do______ you try it.

--- I feel nervous about the coming summer.---- Me , too. Hot weather _____ makes people feel hot, ______ causes serious health problems.

---When did you return to China?---_________________.