与 + Noun + 相反
The word 反 (fǎn) means "opposite," "contrary," or "reverse" and can function as an adjective, adverb, or prefix. It is used to express contradiction or opposition to an expected outcome. For example, 与趋势相反 means "contrary to the trend."
结果和我们预想的正好相反。
Jiéguǒ hé wǒmen yùxiǎng de zhènghǎo xiāngfǎn.
The result was the exact opposite of what we expected.
他嘴上说不在意,行动却恰恰相反。
Tā zuǐ shàng shuō bù zàiyì, xíngdòng què qiàqià xiāngfǎn.
He says he doesn't care, but his actions are exactly the opposite.
与大家的预期相反,房价并没有上涨。
Yǔ dàjiā de yùqī xiāngfǎn, fángjià bìng méiyǒu shàngzhǎng.
Contrary to everyone's expectations, housing prices did not rise.