What made the swans stay there?

参考解析：

细节理解题。根据文章第二段前三句“They were apparently flying to look for a warmer area down south, but they had been caught in the snowstorm. The storm had become too blinding and violent for the swans to fly or see their way. They were trapped on his farm, with no food or shelter, unable to do more than wave their wings and fly in aimless circles.”可知，它们显然是飞往南方寻找温暖的地方，但是它们被暴风雪困住了。暴风雨已经变得太刺眼和猛烈，天鹅们无法飞行或者看到它们的路。它们被困在他的农场里，没有食物，没有庇护所，除了挥舞翅膀和漫无目的地绕圈子外，什么也做不了。故选B。