—Tom must be at home because the light in his house is on.—He be at home because I saw h

问题补充：

—Tom must be at home because the light in his house is on.

—He be at home, because I saw him playing basketball on the playground.

A. must B. can’t C. mustn’t

答案：

解析：由 I saw him playing basketball on the playground（我之前看见他正在操场上打篮球）

可知Tom不可能在家

A一定B不可能C禁止

故选B