挠头

cǐ shì zhēn ràng rén náo tóu

此事真让人挠头。

This is really a knotty problem.

tā náo le náo tóu yī gè zì yě tīng bù dǒng

她挠了挠头，一个字也听不懂。

She scratched her head, not understanding a word.

yǒu yī xiē dú zhě kě néng yǐ jīng zài náo tóu le

有一些读者可能已经在挠头了。

Some of you are probably already scratching your heads.

zhè jiàn shì qing zhēn jiào rén náo tóu

这件事情真叫人挠头。

Things like this are rather troublesome.