A:①是洗涤红细胞,去除血细胞表面的杂质
B:②是溶解DNA,去除不溶于酒精的杂质
C:③溶解DNA,去除不溶于2mol/LNaCl溶液的杂质
D:④稀释NaCl溶液,去除不溶于低浓度NaCl溶液的杂质
I decided____ (buy) it and it was ____ (cheap) than the science book.
给下面的英语句子选择正确的翻译( )
How are you ?