backwards and forwards来回地
词根:backward
adj.backward 向后的;反向的;发展迟缓的
backswept 向后倾斜的;被扫向后面的
adv.backward 向后地;相反地
n.backswept [航] 后掠角
4.Early 20th-century biologists came to a similar conclusion, though they qualified it in terms of probability, stating that there is no reason why evolution cannot run backwards.
20世纪早期的生物学家也得出了类似的结论,不过他们从概率的角度对其进行了限定,称没有理由可以说明进化不能倒退。