These trees____ ____ ____ ____ ____(在.中起重要作用)keeping the earth.

问题描述:

These trees____ ____ ____ ____ ____(在.中起重要作用)keeping the earth.
每空一词
____ ____ ____ ____(对......来说,......是不可能的)such a small child to work out this problem.

很高兴能够在这里回答你的问题,应该为:
These trees (play an important role in)keeping the earth.