--Look! The telephone is broken. Someone damaged it ________ purpose.

--That may be right. But perhaps it was broken _________ accident.

A．on; by

B．by; by

C．on; on

D．by; on

( )是指国债规模的最高额度，或国债的适度规模。

A．国债额度

B．国债结构

C．国债限度

D．国债规模