在问道SC题

If a drug that is already on the market has the potential to help adults and children who have the same disease, or if it is widely used in children and the absence of labeling seems dangerous, the FDA can require that the drug undergo pediatric study.

(A) that the drug undergo

(B) that the drug undergoes

(C) that the drug is to undergo

(D) the drug undergoing

(E) the drug to have to undergo

答案是A，为什么不是B呢，the drug为单数啊~~~

require后面的从句用虚拟语气，省略should

ps:表示命令，建议，要求的词后面的从句要用虚拟语气

LZ,还是先看OG吧

这样比较事半功倍，另外，可以把贴发到专区去，也比较快得到帮助