Jacky is so careless. He       my books and pens       the floor when he walked past my desk just now.

A．turned; over

B．knocked; onto

C．knocked; over

D．turned; onto

订立合同时，一方以欺诈、胁迫手段订立的，损害国家利益的合同属于下列的( )。

A．可变更合同

B．无效合同

C．可撤销合同

D．效力待定合同