The little boy won’t go to sleep his mother tells him a story．
A or B.unless C but D whether
The little boy won’t go to sleep his mother tells him a story．
A or B.unless C but D whether
B
考查连词用法。句意为：“这个小男孩不可能睡觉的，除非他妈妈给他讲个故事。”由句意可知unless“除非”，符合题意。or“否则”；but“但是”；whether“是否”。