Question

Some policeman should be sent to ________ them ________ the trees.

1. A.
   prevent, to cut down
2. B.
   stop, cutting down
3. C.
   keep, to cut down
4. D.
   keep, cutting down

Answer 1

B
导解：stop/prevent/keep sb/sth from doing…阻止……干某事，其中keep的后面不能省略from.