下列基因组成中,是纯合子的是( )
对下列冶铁技术发明年代的排序,正确的是( )
①高炉炼铁 ②灌钢法 ③使用水力鼓风工具
复数 i31+i2=( )
—I an environmental report over the last few days, which should be submitted to the boss tomorrow.