[单选题]Directions: In this part there is a sentence with four choices marked A, B, C and D. Choose the one that best completes the sentence. The teacher,（ ）whether anyone would come to help him, decided to prepare for the experiment by himself.
A
not to know
B
not knowing
C
to have not know
D
knowing not
正确答案：B
题目解析
本题考查对非谓语动词的判断与使用。 句子主干为“The teacher decided to prepare for the experiment by himself.”，逗号中间部分非谓语动词短语作伴随状语，”the teacher老师“与“know知道”之间的逻辑关系为主动，故应使用现在分词形式，D选项knowing not不符合语法规则，故选B。 句意：不知道是否会有人来协助他，这位老师决定自行准备实验。
