The professor,（ ）whether anyone would come to help him, had to prepare for the experiment by himself.
A.正确答案Ddid not know
B.having not known
C.had not known
D.not knowing
The professor,（ ）whether anyone would come to help him, had to prepare for the experiment by himself.
The professor,（ ）whether anyone would come to help him, had to prepare for the experiment by himself.
A.正确答案Ddid not know
B.having not known
C.had not known
D.not knowing
