Wine would often come to Ice's mind. Ice thought it a sign of danger. She must be alert to danger.
Ice的脑海中总会有Wine的影子，她认为这是一种危险的信号，必须保持警惕。
We must be alert to the possibility of danger.
我们必须认识到危险的可能性。
Contagious yawning is thought to be an evolved mechanism for keeping groups alert so they "remain vigilant against danger," Gallup said.
呵欠传染被认为是进化出来用于保持群体的警惕性使群体“在危险面前保持警觉，”盖洛普说。
He knew how to be careful, especially as the rickshaw was his own; however, coming from the country, he was not as alert to danger as city-folk.
他知道怎样谨慎，特别因为车是自己的，但是他究竟是乡下人，不像城里人那样听见风便是雨。
You must be alert to the hidden danger.
你必须对隐藏的危险保持警觉。
We must be constantly alert to this danger.
对此，我们必须保持高度的警惕。
We must be constantly alert to this danger.
对此，我们必须保持高度的警惕。
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