恒湿的英文：
constant humidity

constant是什么意思：
adj. 固定的；不停的，接连不断的
n. 常数；不变的事物

Matter is in constant motion and constant change.
物质总是在不断运动，不断变化的。

A constant guest is never welcome
常客令人厌

The market is in a constant state of flux.
市场行情在不断变化。

The market is a stream that is in constant motion.
市场像河流一样不断地波动。

The speed of light is an invariant constant.
光速是一个不变常数。

humidity是什么意思：
n. 湿度；潮湿

saturation specific humidity
饱和比湿度

Humidity is a measure of moisture in the atmosphere.
湿度是空气内含水分多少的量度。

The day is overcast and humid.
天气多云潮湿。

The humidity is relatively low.
湿度相对较低。

The heat and humidity were insufferable.
高温和潮湿让人难以忍受。