共栖
参考答案：
一方受益，另一方不受害。获益的一方称为共栖者，是主动的；另一方为宿主，是被动的。
I looked out and found the ground ______ with white snow. [ ]
A. covered
B. covering
C. to cover
D. is covered
论述房地产经济周期与宏观经济周期的关系？
