—Perhaps Johns not in.—.Look，the lights on.A. Yes，he can be at homeB. No，he couldnt go

—Perhaps John's not in.
— .Look，the light's on.
A. Yes，he can be at home
B. No，he couldn't go out
C. Yes，he must be at home
D. No，he needn't go out

A. Yes，he can be at homeB. No，he couldn't go out(答案→)C. Yes，he must be at homeD. No，he needn't go out解析：由“Look，the light's 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”。

哦，回答的不错