I didn’t know ________ they could pass the exam or not．A．why B．when C．that D．whether

I didn’t know ________ they could pass the exam or not．A．why B．when C．that D．whether
I didn’t know ________ they could pass the exam or not．
A．why B．when C．that D．whether

I didn’t know ________ they could pass the exam or not．A．why B．when C．that D．whether
D,我不知道他们是否能通过考试,因为Weather.or not 是一个固定搭配,是否