He isn't at home.He is____.a.out b.outside

问题描述:

He isn't at home.He is____.a.out b.outside
WHY?
THANK U

out是副词,outside是介词
介词后面要跟名词的,譬如outside the door
副词则可以单独使用,如 he's there; he's here
所以这里应该选A