穿过地理梯度, 莱文斯预料有分布区不重叠的小种或近群种.Across geographic gradients, Levins expects allopatric races or coenospecies exist.航空磁梯度仪在六十年代中期交付使用.The airborne magnetic gradiometer came into use in the middle 1960 s.这说明水动力条件具有很明显的位能梯度.Thi...
A cicada throws its slough.蝉是要蜕皮的.A cicada sloughs off its old skin every spring.蝉每年春天蜕皮.Other insects such as cicada have 3 periods in its lifecycle.而另一些昆虫,像蝉,一生中有3个阶段.The cicada made by green jade is the symbol of luck...
牛群在湿地上吃草。Cows were grazing on the marshes.她赶着牛群穿过荒野.She drove the herd of cattle through the wilderness.他精心照料着牛群,不使它们瘦下来.He took care to keep the cattle from falling off....