—_____ are they doing?
—They are running. [ ]
A. Who
B. Whose
C. What
D. Where
C
房屋铝合金隔墙破坏属()。
A.室内设备破坏
B.承重墙破坏
C.结构性损坏
D.装修损坏
简述科斯定理的特点?