对生物个体而言,所谓有利变异是指( )
A:对所有生物有利的变异
B:对生物个体生存有利的变异
C:对人类有利的可遗传变异
D:对人类不利的不可遗传变异
距关,毋内诸侯,秦地可尽王也。
–I like the weather in Kunming. It's warm all year long.—Yes. And the temperature stays zero all the time.