下列哪些是引起单纯性甲状腺肿的原因?()
A．缺碘
B．高碘
C．木薯
D．青春发育期
E．碳酸锂
参考答案：A, B, C, D, E
腰椎管狭窄症的典型症状为________________，本病的最大特点是____________________。
The meat you bought last week () terrible. It () bad.
A．smells; must go
B．smells; must have gone
C．is smelt; must go
D．is smelt; must have gone
