坡上一棵粗樹(shù)，坡下一棵禿樹(shù)。坡上粗樹(shù)看禿樹(shù)樹(shù)禿，坡下禿樹(shù)看粗樹(shù)樹(shù)粗。粗樹(shù)樹(shù)粗樹(shù)不禿，禿樹(shù)樹(shù)禿樹(shù)不粗。粗樹(shù)比禿樹(shù)粗，禿樹(shù)比粗樹(shù)禿。