Is that your bike, in front of the black one?－No. It’s ______.

_____of the warm water _____already been used up.

The work is really very difficult; _________ it’s very interesting.[ ]

You look pale. What’s _______ with you? —I have _______ headache.

We’ll go to Qing Yuan Mountain tomorrow. Why _____ join us? —That’s a good idea. [ ]