Listen to the conversation and choose the correst answer.
A. $157.4
B. $15.74
C. $175.4
D. $17.54
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Listen to the conversation and choose the correst answer.
A. $50.80
B. $15.80
C. $15.08
D. $50.08
Listen to the conversation and choose the correst answer.
A. $549
B. $594
C. $599
D. $595
重量法是颗粒物监测的基准方法。
A. 对
B. 错
重量法测定环境空气中PM10和PM2.5，将颗粒物截留在已知质量的滤膜上，根据采样前后滤膜重量之差及采样体积，即可计算浓度。
A. 对
B. 错
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