Question

—He looks very happy. He ____have passed the exam,
—I guess so. It’s not difficult after all.

A．should

B．could

C．must

D．might

Answer 1

C

本题的含义是，他看起来很开心，那么他一定通过了考试才符合句意，must可以表示一定的意思，故本题选C。