Once a computer is put into water, the system _______ and cannot repair itself.

A．breaks down

B．breaks through

C．breaks out

D．breaks up

走行于桡神经沟内的动脉是（）

A.桡动脉

B.腋动脉

C.旋肱后动脉

D.肱深动脉

E.旋肱前动脉