食品污染可概括为生物性污染、化学性污染和放射性污染，下列属于生物性污染的是
A．昆虫
B．X射线
C．多环芳烃
D．醇类
E．醛类
参考答案：A
— Must they clean and tidy the classroom now?
— No, they . It after school in the afternoon. [ ]
A. mustn't; must clean
B. needn't; must clean
C. mustn't; need be cleaned
D. don't have to; can be cleaned
腕管综合征的治疗目的不包括（）
A.消除水肿
B.消除压力
C.延缓肌肉萎缩
D.恢复运动功能
E.缓解疼痛
