据估计,在高等生物中,大约有105~108个生殖细胞中,才会有1个生殖细胞发生基因突变.这说明基因突变( ) A.普遍存在 B.随机发生 C.不定向 D.频率很低 答案:解:在高等生物中,大约有105~108个生殖细胞中,才会有1个生殖细胞发生基因突变.这说明基因突变的频率很低. 故选:D.
-I think it's time for us to leave now.
-________.
[ ]
A.
See you later
B.
Go ahead,please.
C.
You,too.
D.
Thanks.