The message is very important so it is supposedas soon as possible.A. to be sentB. to sen

问题补充：

The message is very important, so it is supposedas soon as possible.

A. to be sent

B. to send

C. being sent

D. sending

答案：

(答案→)A. to be sent

B. to send

C. being sent

D. sending

解析： be supposed to do是固定搭配。又因it（the message）与send因为被动关系，故用动词不定式的被动语态。