Madonna ____a straight A student,but it was dancing that she was really crazy about.   

A．must be

B．could be

C．must have been

D．could have been

在检验检疫机构签发检验检疫证单后，报检人要求补充内容的，应办理申请手续，填写( )，并出具书面证明材料。

A．报检申请单
B．补充申请单
C．更改申请单
D．变更申请单