Swallow, by your comprehension, may be a small slender songbird, with long and forked tail, and black and white and V-shaped streak on the chest.

• 燕子，根据你的理解,也许是一种纤细灵巧的鸣鸟，长而叉形的尾，黑白相间，胸口处有V型的条纹。