如果他挠头，你也挠头。

If he scratches his head, you scratch your head.

挥手表示欢迎和告别，而挠头则表示不知所措。

Waving can mean welcome and farewell, whereas scratching your head may indicate that you are at a loss.

她精于分析，令人惊讶，能够解决让警方挠头的各种奇案。

She uses her surprising analytical acumen to solve mysteries that have stumped the police.

劳苦是一种什么感觉呢？你面临一大堆麻烦，日常的问题使你挠头，你觉得被生活击溃了。

What does it feel like to be weary? You have trouble concentrating. The problems of the day are like a claw in your brain. You feel pummeled by life.