征象

例句：

1. 1. The sudden drop in the stock price is a warning sign for investors.
   股票价格的突然下跌是投资者的一个警示信号。
2. 2. The new policy has raised concerns about its potential impact on the economy.
   新政策引发了对其可能对经济影响的担忧。
3. 3. The discovery of a new species is often a sign of progress in scientific research.
   新物种的发现往往是科学研究进步的标志。