医生说这个病是极其罕见的。

Yīshēng shuō zhège bìng shì jíqí hǎnjiàn de.

The doctor said this illness is extremely rare.

我对你感到极其失望。

Wǒ duì nǐ gǎndào jíqí shīwàng.

I’m extremely disappointed in you.

这次我们公司受到了极其严峻的考验。

Zhè cì wǒmen gōngsī shòudào le jíqí yánjùn de kǎoyàn.

This time, our company faced an extremely severe test.