So well         in 2009 that the world has agreed that it was the year of China.

A．did China perform

B．China has performed

C．was China performed

D．China is performing

因不可抗力使合同不能履行时，( )。

A．一方提出解除合同需经对方同意

B．双方就能解除合同

C．需双方协商一致才能解除合同

D．当事人一方可单方提出解除合同