We should go to school at 8:00 ______ school mornings. [ ]
A. at
B. in
C. on
D. of
答案:C
在细菌lac和trp操纵子上,为什么阻遏蛋白编码基因不一定要和结构基因连在一起
面向规模的度量是以软件的()为基础的直接度量。