The serious problem ____ mankind now is how to protect the environment effectively.A.faces B.facing C.is faced with D.to face

分类: 作业答案 • 2022-02-11 14:32:57

问题描述：

The serious problem ____ mankind now is how to protect the environment effectively.
A.faces B.facing C.is faced with D.to face

答

B对 The serious problem facing mankind 是动名词的复合结构

答

B,分词短语做后置定语