Question

—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

1. A.
   must
2. B.
   can’t
3. C.
   mustn’t

Answer 1

B
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