环境空气之哦那个颗粒物样品采集结束后,取滤膜时,发现滤膜上尘的边缘轮廓不清晰,说明什么问题?应如何处理?
参考答案:
表示采样时漏气,则本次采样作废,需重新采样。
—Look at the boy running on the ground. Is it Davis?
—It _____ be him. I saw him go to the teacher's office just now. [ ]
A. must
B. can't
C. could
D. might
下列选项中,不属于多孔吸声材料的是( )。
A.聚苯乙烯泡沫塑料
B.玻璃棉
C.脲醛泡沫塑料
D.麻棉毛毡