—There is a lot of smoke ing out of the teaching-building there.
—Really?It be a fire,most probably.
A. can
B. ought to
C. have to
D. must
网友回答
A. can
(答案→)B. ought to
C. have to
D. must
解析：考查情态动词。由most probably可知说话人的语气并不非常肯定，所以用ought to表示推测，语气比must弱一些，给自己留有一些余地。