barometer

The needle on the barometer dropped suddenly, signaling that a major storm was approaching.

(Chinese) 气压计上的指针突然下降，预示着一场大风暴即将来临。

Economists often use consumer spending as a barometer to measure the overall health of the nation's economy.

(Chinese) 经济学家经常把消费者支出当作衡量国家经济整体健康状况的晴雨表。