题干
33. There's no light on - they______ be at home.
A：can't
B：mustn't
C：needn't
D：shouldn't
答案(点此获取答案解析）
A
A：can't
B：mustn't
C：needn't
D：shouldn't
是制作电木的原料．下列围绕此物质的讨论正确的是（ ）