Please fill in the blank with the appropriate form of A WORD or A PHRASE. There was an ______20% increase in the sales on double 11 th day. ( astonishing; so surprising that it is difficult to believe )
【简答题】某市对大气进行监测,发现该市首要污染物为可吸入颗粒物PM 2.5 (直径小于等于2.5μm的悬浮颗粒物),其主要来源为燃煤、机动车尾气等。因此,对PM 2.5 、SO 2 、NO x 等进行研究具有重要意义。 请回答下列问题: (1)将PM 2.5 样本用蒸馏水处理制成待测试样。 若测得该试样所含水溶性无机离子的化学组分及其平均浓度如下表: 离子 K + Na + N S N Cl - 浓度/mo...