在基因工程中,科学家常用细菌、酵母菌等微生物作为受体细胞,主要原因是( )
A:结构简单,操作方便
B:遗传物质含量少
C:繁殖速度快
D:性状稳定,变异少
It was the boy, rather than his brothers, that _________ for what they had done.
亚洲地跨的温度带是____、____、____三带。
下列气候特点属于非洲的是( )
We can read 10: 15 like this: .