题目

―Where is Michael? I cannot find him anywhere.  ―He ______ have been off long. I saw him study in the room just now.  A．shouldn't                 B．can't             C．mustn't           D．needn't   答案：B19．计算：（-2）3+（-$\frac{2}{3}$-$\frac{5}{6}$+$\frac{11}{12}$）×（-24）．