Only by returning the forest to the mountains and letting the water in the lake can Nanjing be bluer, the water greener, and the people more beautiful. This shows:. ['Only when the sky is bluer and the water is greener can Nanjing be more beautiful.', 'As long as the forest is returned to the mountains and the water is in the lake, Nanjing will be bluer, the water greener, and the people more beautiful.', "If you don't return the forest to the mountains and let the water in the lake, Nanjing will not be bluer, the water greener, and the people more beautiful.", 'Only returning the forest to the mountain can make the water in the lake.']