Not only.but also 倒装句

问题描述:

Not only.but also 倒装句
____the old man to the hospital but he also paid for the medical fee
A.Not only did the student send
B Not only the student sent
C Not only did the student sent
D The student did not only sent
跪求CD不能选的原因

C项Not only did the student sent中已经有助动词DID了,所以动词SEND需要用原型.D项The student did not only sent完全不符合NOT ONLY语句(也是通用的提前副词成分的)倒装的规则.