scare ： 指暂时不易发现、不存在或数量不足，供不应求的东西。
rare ： 指难得发生的事或难遇见的`人或事，侧重特殊性。
例句：
1. It remained an exceptionally rare book until it was reprinted in 1918.
在1918年再版之前，这本书一直非常罕见。
2. It was a rare pleasure to see him in action.
看他打球是一种享受。
3. As we approached the summit we were vouchsafed a rare vision.
快到山顶时，我们有幸看到了难得一见的景象。
4. Rare birds preen themselves right in front of your camera.
很少有鸟类会在镜头面前梳理自己的羽毛。