亚甲蓝分光光度法测定水中阴离子表面活性剂中,在绘制校准曲线时,应使用与样品测定时()的三氯甲烷和亚甲蓝溶液。
A.同一批
B.同一厂家
C.提纯的
参考答案:A
The silence of the library is sometimes broken by a sudden cough or the sound of pages __________.
A.turning
B.turned
C.being turned
D.having turned
Chen Jie has . Amy has .[ ]
A. long hair; short hair
B. new; old