[tū rán]
sudden; abrupt; unexpected; suddenly; abruptly; unexpectedly
come a cropper
突然失败
go [fly] off at a tangent; go off on a tangent
突然离开话题
suddenly stop
突然停止
This news is really much too sudden
这消息实在太突然了。
In the afternoon it rained suddenly.
下午天突然下雨了。
I shouldn't be surprised if he cropped up this evening.
如果他今晚突然出现， 我并不感到惊讶。