The remaining sheep 剩下的羊

The teacher said: "If the shepherd put twenty sheep out to feed on the grass in a field, five of them jumped a fence, how many sheep would be left?"

"None," called out little Mac. The teacher said: "I am surprised that you can't count correctly. I know that you are good at arithmetic, but you have made such a mistake now."

Little Mac said: "You know arithmetic, teacher, but you don't know sheep. I know that if one sheep jumped, the rest will follow it to do the same."

老师说：“如果牧羊人把20只羊放到牧场上去吃草，有5只羊跳出了围栏，还会剩下多少只？”

小麦克大声回答说：“一只都没有。”老师说：“我很惊讶，你竟然不会算数。我知道你的算术很好的，现在竟会出错。”

小麦克说：“老师，你懂算术，但你不了解羊。英语小故事我知道，若是有一只羊跳了出去，其余的就会跟着她跳出去。”