题目

. When it _________ high technology, he is completely at a loss.    A. refers to             B. comes to              C. happens to          D. speaks to 答案：B除去下列物质中含有的少量杂质（括号中的物质）的方法，错误的是（ ）A.NH4Cl溶液（I2）用CCl4萃取B.NO（NH3）通过水洗涤C.NH4Cl（NaCl）加热固体混合物D.N2（NO2）通过水洗涤