用可见分光光度计测定时,下列操作中正确的是()
A.比色皿外壁有水珠
B.手捏比色皿的毛面
C.手捏比色皿的磨光面
D.用普通白纸去擦比色皿外壁的水
参考答案:B
Linda loves music and she often plays ______ violin in her free time.[ ]
A. a
B. an
C. the
D. /