问题
选择题
—There is a lot of smoke coming out of the teaching-building there.
—Really?It _________ be a fire,most probably.
A．can
B．ought to
C．have to
D．must
答案
B
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。