he_____ writing the paper now.he hadn't wriiten a single word when i left him ten minutes ago.
A shouldn't be
B can't have finished
C can't be
D mustn't have finished
參考答案:B.首先要明白要说的是“我走的时候他还没开始呢,他现在不可能写完”,而这是说这句话的人的猜测。表否定猜测只能用can't,mustn't是“禁止”,而shouldn't是“不应该做某事”,“shouldn't have”的话是不应该已经做某事(而事实上做了)。c的话语意就不对啊,刚才没开始写现在就不能在写了吗?