The doctor said that his brother had ( ) at once.

The doctor said that his brother had ( ) at once.
A、to operate
B、to be operated
C、to operate on
D、to be operated on
【正确答案】：D
【题目解析】：to be done 表达将来，be operated on 做手术，句子含义是医生说他的弟弟要动手术。