that man _____ be the headmaster ,because he always stands here at this time.（填适当的情态动词）
问题描述：
that man _____ be the headmaster ,because he always stands here at this time.（填适当的情态动词）
答
填must.
后面有表示原因的推断.所以这里是肯定.because的原因是最强的.所以是很肯定的推断.