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单项选择题
A.50
B.70
C.35
D.100
单项选择题
A.30mg/m3(20ppm)
B.45mg/m3(30ppm)
C.75mg/m3(50ppm)
D.150mg/m3(100ppm)
单项选择题
A.30mg/m3(20ppm)
B.45mg/m3(30ppm)
C.75mg/m3(50ppm)
D.150mg/m3(100ppm)
单项选择题
A.阈限值
B.安全临界浓度
C.危险临界浓度
D.4.3ppm以下
单项选择题
A.50%
B.60%
C.80%
D.100%
单项选择题
A.防喷单根、防喷立柱
B.应急旋塞、防喷立柱
C.应急旋塞、防喷单根
D.防喷单根、应急旋塞
单项选择题
A.常关、常开
B.常关、常关
C.常开、常开
D.常开、常关