One of them wrote to us out of the blue several years later.数年后他们中的一人突然给我们写了一封信。Her son, who left her more than thirty years ago, came out of the blue.她三十多年前离开的儿子出乎意料地回来了.The whole thing was a bolt out of the blue.这件事,整个...

out of the blue的音标：out of the blue的英式发音音标为：[aut ɔv ðə blu:]out of the blue的美式发音音标为：[aʊt ʌv ði blu]...

出其不意，出乎意料...