Grandpa is ill.A doctor must -----at once.

Grandpa is ill.A doctor must _____at once.
A.send away. B. be send for. C. send for. D. be send up. 这道题选什么＞＜
答：E, be sent for
译：爷爷病了.必须马上请个医生来.
析：send (sb). for a doctor 是的（派个人去）请个医生. 被动语态就是：a doctor be sent for
本句为We must send for a doctor at once的被动语态句子.
楼主不小心将BD的sent 打成了send了吧?请再检查一下原题句的四个选项.