The message is very important , so it is supposed as soon as possible .
A. sending
B. to send
C. being sent
D. to be sent
网友回答
A. sending
B. to send
C. being sent
(答案→)D. to be sent
解析：：考查固定结构和语态。Be supposed to do sth应该做某事；根据句意是被动语态。句意：这个信息非常重要，所以应该立刻被送出去。故D正确。