—I’m sorry, but the manager isn’t here yet. Shall I have him call you when he comes back?

—No, I’ll call him later. If I call again in half an hour, do you think he ____?

A．arrives

B．has arrived

C．will arrive

D．will have arrived

图5-4所示受扭网杆的应变能为（）。

A．A

B．B

C．C

D．D