He feels that his health ____ owing to ____ a long walk every other day.
I fixed my eyes upon the newcomer, wondering whether I ________ him somewhere before.
一I’m sorry! I would have taken him to hospital if I had known he was seriously ill.一But ______ .
The question that puzzled them is ____ they can get rid of the air pollution in the area.
It is reported that many a new house ____ at present in the disaster area in Gansu Province.
_____ on a clear day, far from the city crowds, the mountains gave him a sense of peace.