Shānqū tiānqì biànhuà wúcháng, chūxíng yào dài sǎn.
Weather in the mountains is unpredictable — bring an umbrella.
Tā de qíngxù biànhuà wúcháng, nányǐ xiāngchǔ.
His moods are unpredictable — he's hard to get along with.
Gǔshì biànhuà wúcháng, tóuzī xū jǐnshèn.
The stock market is volatile — invest with caution.
