你知道外国人常说的 out of the blue 是什么意思吗？

　　out of the blue

　　出乎意料，突如其来

　　释义：

　　If something happens out of the blue, it is completely unexpected. 出乎意料地;突然

　　例句：

　　One day, out of the blue, she announced that she was leaving.

　　One of them wrote to us out of the blue several years later.