shake
The German word 'schütteln' is used in the same way as the English word 'shake'. It can refer to the action of moving something back and forth quickly, such as shaking a bottle to mix its contents. It can also be used metaphorically, such as 'to shake off' a bad feeling or habit. Additionally, 'schütteln' can be used as a noun, referring to the act of shaking.
She shook her head.
This is a direct usage of 'schütteln' meaning 'to shake'. It is used here in past tense to indicate that the action has already took place. It's a common phrase when someone disapproves or disagrees with something.
Please shake the bottle well.
The phrase is an example of command, ordering someone to shake the bottle. 'Gut' means 'well', emphasizing that the bottle should be thoroughly shaken.
I have to shake my head.
The phrase exemplifies the usage of 'muss' (must), expressing a necessity or obligation to do the action - shaking the head in this case. In German, the verb often comes at the end in clauses introduced by a modal verb.