题目

下列有关鉴定实验操作步骤的叙述中，正确的是（ ）A.用于鉴定还原糖的斐林试剂甲液和乙液可直接用于蛋白质的鉴定B.花生子叶中脂肪的鉴定需借助显微镜才能看到被染成橘黄色的脂肪颗粒C.鉴定还原糖时，要在加入斐林试剂甲液摇匀后，再加乙液D.用于鉴定蛋白质的双缩脲试剂A液和B液混合均匀后再加入到含样品试管中，且需现用现配–Where are the students? How could they keep us waiting for so long? –They started an hour ago and they ____ be here in fifteen minutes, I thinkA.canB.wouldC.shouldD.must