cull|culled|culling

农场主不得不宰杀一些羊羔以控制羊群数量。

The farmer had to ___cull some lambs to control the flock size.

农场主每年都会淘汰一些病弱的鸡，以保持鸡群健康。

The farmer ___culled the sick chickens every year to maintain a healthy flock.

农场主正在淘汰病弱的羊只以保持羊群健康。

The farmer is ___culling weak sheep to maintain the herd's health.