Because if you don't they have a tendency to get too hot and overflow.

因为如果你不这样做，它们就会变得太热而溢出。

Another thing to keep in mind is you don't want this pan to get too hot, otherwise when you add the butter, it'll go berserk and attack you.

另一件要记住的事情是你不希望这个平底锅变得太热，否则当你添加黄油时，它会发疯并攻击你。