a cloudless blue sky的用法和样例：
- Overhead, a plane hired by the Australian Greens Party drew the words "Free Tibet" in a cloudless blue sky, while a second aircraft later towed a banner reading "Go Go Beijing Olympics.
- A cloud is a mass of vapor in the sky.
- It was the beginning of a day in June; the deep blue sky unsullied by a cloud, and teeming with brilliant light.
- A lone cloud floated in the blue sky.