a wan complexion的用法和样例：
- The sick boy gave the doctor a wan smile.
- Life is mostly beautiful, don't wear a wan smile!
- Jackson often insisted that his wan complexion was the result of treatment for a skin disorder called vitiligo, but that did not explain why his once-broad nose became long, sleek and pertly tipped.
- The farther you send data over a WAN, the more it costs.