问题补充:
—Perhaps Johns not in.
—.Look,the lights on.
A. Yes,he can be at home
B. No,he couldn go out
C. Yes,he must be at home
D. No,he needn go out
答案:
A. Yes,he can be at home
B. No,he couldn go out
(答案→)C. Yes,he must be at home
D. No,he needn go out
解析:由“Look,the lights on”可知他此刻一定在家里,所以用must be at home表示“对事情的肯定推测”。