程序外DNA合成试验的遗传学终点为()
A.基因突变
B.染色体畸变
C.DNA完整性改变
D.细胞坏死
E.细胞恶性转化
参考答案:C
Mark Twain ______ school and began to work at the age of twelve.
A.left
B.leaves
C.will leave
D.leave
空气消毒机的适用范围是什么?