分包合同的解除实质上是清退分包方，包括依（）和依法律规定解除两种。
参考答案：合同约定解除
---What does Tom’s uncle do?
---He is a teacher. He __________ physics at a school now. [ ]
A. will teach
B. has taught
C. teaches
D. taught
设连续型随机变量X的分布函数为F(x)，密度函数为f(x)，而且X与-X有相同的分布函数，则
A．F(x)=F(-x)．
B．F(x)=-F(-x)．
C．f(x)=f(-x)．
D．f(x)=-f(-x)．
