广播电视英语短句 第 218 课：循环放牧-5

The pasture is then kept empty until the grass grows to more than fifteen centimeters high. 然后这个牧场保持闲置直到草长到超过 十五厘米 高。

Experts say sheep and goats may require special preparations. 专家们说绵羊和山羊也许需要特别的准备。

They may need stronger fences than other animals. 它们可能需要比其他动物更结实的围栏。

And while they eat the grass, they may need guard animals to protect them from animals that would like to eat them. 并且当它们吃草时，它们可能需要有警戒的动物以保护它们不受可能吃它们的动物的攻击。