The ducklings are cheeping.小鸭咻咻地叫着.The ducklings are swimming close to their mother.小鸭子紧挨着母鸭游水.The ducklings plumped into the water.小鸭子扑嗵扑嗵跳入水中.The ducklings have shed their yellow down.小鸭褪了黄毛....
卵子排出后可存活12至36小时。Once the ovum is released it has a lifespan of 12 to 36 hours.在同一发情期排出两个或数个卵子.Two or more ova are shed during the same heat period.到第11天卵子着床嵌入子宫内壁.By day 11 the ovum begins to attach and implant in the li...