通气管高出屋面不得小于（），且应大于最大积雪厚度，通气管顶端应装设风帽或网罩。
参考答案：0.3m
English_______ in many countries, but Chinese_____ their own language. [ ]
A. is spoken ; speaks
B. speaks; is spoken
C. is spoken ; speak
D. is spoken; is spoken
甲状腺含有激素，有时留在脖头肉上。人误食可引起头痛、恶心等中毒反应，甲状腺素理化性质稳定，需要（）摄氏度时甲状腺素才被破坏。
A.600
B.300
C.200
D.800
