__what to do,he decided to go to Mr Black for help. A.Not knowing B.Not having known
问题描述：
__what to do,he decided to go to Mr Black for help. A.Not knowing B.Not having known
C.Knowing not D.Having not known
说明理由谢谢，答案选择A
答
A,这个是动词ing做状语,对于非谓语动词的否定,对于v-ing是在v-ing前加not,对于不定式to do的否定是在to 前加not,成为not to do.所以排除C、D.对于B,因为“know what to do”有“decide to go……”之间没有发生的先...