一When did you learn the news that Obama made a trip to Canada as President?一 ____ was on my return．

——Your coffee smells great！——It’s from Mexico. Would you like ____  ?

–There is _______ on using mobile phones at the gas station. --Do you mean talking on the mobile phone ________ at the gas station?

I told your friends how to get to the hotel, but perhaps I ____have driven her there.

—What will the weather be like tomorrow?—I think it will be________as it was yesterday.