旋光法检查药物中的杂质是
A.利用吸附或分配性质的差异 B.利用旋光性质的差异 C.利用对光吸收的差异 D.利用溶解行为的差异 E.利用颜色的差异
参考答案:B
有一张长32cm,宽8cm的长方形彩纸,剪成边长为2cm的小正方形,最多可以剪多少个?
It took him a long time to _________ the skills he needed to become a professional artist.
A.require
B.acquire
C.inquire
D.gather