__________ is announced in today’s paper,they have succeeded in solving many problems in accordance with the new theory.

A．It

B．That

C．What

D．As

如果扰流板液压作动筒已经伸出，这时突然失去液压，会出现下列什么现象（）

A.扰流板自动收回

B.扰流板保持中立

C.备用液压会立即给扰流板作动筒供液压

D.扰流板保持在伸出位，或由气动原因向收回位移动