—Look at the boy running on the ground. Is it David?

—It      be him. I saw him go to the teacher’s office just now.

A．must

B．mustn’t

C．can’t

D．might

根据有关担保法的规定，用以下（）财产设立抵押时，必须办理登记。

A.电脑

B.林木

C.企业的设备

D.船舶

E.电视