Silicosis that develops___years after first exposure to higher concentrations of silica dust()
A. <5
B. 5-10
C. 10-15
D. >15
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急性胆囊炎致病菌的主要来源()
A. 由肠道至胆道
B. 淋巴管道
C. 邻近脏器
D. 经门静脉而来
E. 经动脉系统而来
The respirable dust is defined by those particles≤()μm size range
A. 44
B. 10
C. 70
D. 2