I'm going out． I'll be back _____ an hour．（ ）
A．atB．onC．inD．from
Our teachers often tell us how to teach _____（ ）
A．themselvesB．ourselvesC．yourselves
I think eating ____is good for health （ ）
A．tomatoesB．bananaesC．egges
I find___pen on the ground．Whose is ___pen？（ ）
A．a，theB．the，aC．a，a
Frank knows much about the city because he ______ there many times．（ ）
A．wentB．has goneC．has been
Could you please tell me _________？（ ）
A．where does he liveB．where he lives
C．where he live