Tom was ________ honour for our school  when the meeting came to ________ end. [ ]

A . an; an  

B. an; the

C. the; /  

D. /; an

与静止变流器相比，旋转变流机不具备的特点是：（）.

A.体积重量大

B.效率高

C.耗能大

D.可靠性低