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

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. can B. mustn’t C. can’t

答案：

解析：can能，mustn’t禁止，can’t不能。句意：汤姆一定在家，因为他家的灯亮着。他不能在家，因为我看见他正在操场打篮球。故选C。