The warning we were given as children ________ an apple a day keeps the doctor away may，in fact，have a scientific explanation.

Would you please drive _________________ My train is leaving.—I’d like to, but safety comes first.

ists are tryingto develop a special material, ________ they will make use of in spacecraft

____ day it is! —Let’s go out and enjoy the sunshine.

I think he is taking an active part in social workI agree with you ______