筑巢

例句：

1. 1. The bird is busy building its nest in the tree.
   这只鸟正在忙着在树上筑巢。
2. 2. She carefully built her own house to escape from the city.
   她小心地为自己建了一座房子，以逃避城市生活。
3. 3. Many birds build their nests in the mountains during winter.
   许多鸟儿在冬天会在山上筑巢。