sure signal

例句：

1. 1.The sure signal that the meeting is going well.
   会议进行得很顺利的确凿信号。
2. 2. The sure signal that she'll be late again.
   她再次迟到的确定信号。
3. 3. The sure signal that the storm has passed.
   暴风雨已经过去的确定信号。