The teacher,（）whether anyone would come to help him, decided to prepare for the experiment by himself.
A、
not knowing
B、
not to know
C、
knowing not
D、
to have not know
【正确答案】：A
【题目解析】：
本题考查的是非谓语动词doing作伴随状语的使用。
句子的主干为：The teacher decided to prepare for the experiment by himself. 中间部分为伴随状语，the teacher 和动词know 是逻辑上的主动关系，所以用doing形式，C选项knowing not不符合英语语法规则，故选择A选项。
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。
