_____arriving home,he saw the letter behind the door on the floor.A.Over B.In C.Upon D.At答案为什么是C,不能是D?
问题描述:
_____arriving home,he saw the letter behind the door on the floor.
A.Over B.In C.Upon D.At
答案为什么是C,不能是D?
答
C
on/upon doing 一怎么样
固定搭配
)