John, look at the time. ____ you play the piano at such a late hour?
I can never forget the days _____ we worked together and the days _____ we spent together.A. when; which B. which; when C. what; that D when; when
The Beijing express had _____ on time when we hurriedly got to the platform.
—Have you thought of a topic for your speech yet? —No, I______a lot about it, but I haven’t decided.
The users of this new mobile phone can check e-mails _____ they happen to be.
What_____pleasant surprise! I’ll tell Richard about it____minute he comes home.