题目

只用一种试剂就能把Na2SO4、NaCl、(NH4)2SO4、NH4Cl四种溶液区分开来，这种试剂是A.AgNO3     B.NaOH    C.BaCl2     D.Ba(OH)2 答案：DHe is not ____ to be present at the meeting tonight.A.possibleB.likelyC.probablyD.perhaps