问题
单项选择题
井下二氧化氮最高允许浓度是（）
A、0.00015%
B、0.00025%
C、0.00035%
D、0.0005%
答案
参考答案：B
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井下二氧化氮最高允许浓度是（）
A、0.00015%
B、0.00025%
C、0.00035%
D、0.0005%
参考答案：B
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| Dear friend, I lost my 1 . A school ID card, a pencil sharpener and 2 are in it. If you find it, please call me at 3 . You can come to my classroom, too. I am in Class 4 , Grade Two. Thank you very much. 5 |