The rural workforce has been flowing in to the cities ever since the open door policy was adopted.
自从改革开放政策实施以来,农付劳动力正不断流向城市。
And why only snakes? Cats, for instance, would be greatly helped; no running fights with large, fierce rats or tussles with grown rabbits -- just a bite and no more effort needed.
为什么只有蛇才有毒液呢?譬如说,如果猫有毒液,那对猫会大有帮助,它就不必再和又大又凶的老鼠边跑边博斗了,也不必再和大兔子扭斗了,只要咬一口,就不必再费大力气。