—Where ____ Margaret have put the empty bottles? —She ______ them away. They must be somewhere. A.can; can’t have thrown B.must; needn’t C.must; must have thrown D.can; must throw 答案:A 解析: 本题考查情态动词+have done表示对过去事实的推测的用法。must have done用于肯定句中,疑问句否定句中应用can could代替must。故选A。某同学在实验报告中有以下实验数据记录,其中合理的是( )A.用托盘天平称取11.72g食盐B.用100mL的量筒量取25.00mL盐酸C.用pH试纸测得某氯水的pH为4D.用0.2000 mol/L盐酸滴定20.00mL未知浓度NaOH,用去22.40mL盐酸溶液