a warning sign的意思|示意

I even spotted a warning sign, next to an elevator, that read, “Nihil obstat elevator.”

我甚至发现了警示牌，靠近电梯，写着“无障碍电梯”。

He set up a warning sign on the bank of the river.

他在河边竖起了一个告示牌。

That's a warning sign.

这就是一处问题迹象。

In nature, color changes can signal the onset of a new season, or offer a warning sign to keep predators at bay.

在自然界中，颜色的变化可以是一个新季节开始的信号，或者提供了一个警告远离海湾食肉动物的信号。

They can also turn yellow. Yellowing can be a sign of too much water. But it can also be a warning sign of too little water.

泛黄又可能是水分过剩的迹象，或者是植物太缺水的警报信号。

It really should be a warning sign, after all, can not swim in the swimming pool is very dangerous to play in the swimming pool.

这确实应该设立一个警示牌，毕竟不会游泳儿童在游泳池里玩耍是十分危险性。