27．After the adventure, the children returned home, ______.

_______ after the race that he didn’t know what to saybefore so many reporters

New York is known ________ the world ________ a busy trade centre.

The scientific study shows that once _____ cigarettes, one will find it hard to get out of it.

Look! A man is cutting a tree on the moon.–It ______ be true. The teacher said there is no air on the moon.