慢性缩窄性心包炎，手术指征最强的临床表现是

A．胸部X线检查显示心包钙化
B．心电图显示QRS波低电压
C．超声心动图显示心包腔内积液
D．心导管检查显示右房右室舒张压升高
E．周围静脉压明显升高

I am sorry. I______finished it by last Monday, but I have been too busy.

A．must have

B．may have

C．ought to have

D．might have