We must know what we should do and what we should avoid _______ a good impression on others in public places.

Please tell me the way you thought of _______ to stop smoking.

 ________on a clear day，far from the city crowds，the mountains give him a sense of peace.

Now when people refer to England, you find Wales ____ as well．

He ran all the way to the station only _______________ the train had already left.