Variation among humans is limited to the possible permutations of our genes.人类的变异受限于我们的基因可能存在哪些排列。Genes are those tiny bits of biological information swapped in sexual reproduction.基因是在有性繁殖中交换的微小生物信息。The technique has be...
Most stars probably have their quota of planets, meteorids, comets, and asteroids.多数恒星也许还拥有若干行星 、 流星 、 彗星和小行星.As comets go, it is a whopper.就彗星而言,它可是个庞然大物。...unnamed comets and asteroids.未命名的彗星和小行星The earth crosses the t...