—The old man is ill. He ________ to the hospital at once.
--Don’t worry. A doctor _________to come already.

A．must be sent , has asked

B．must send, have asked

C．must be sent, has been asked

D．must send, have been asked

科目 英语   题型 单选题   难度 中等

知识点： 比较介词 语态的辨析