A customer sent a screenshot asking which one to install.

Looking at the picture, above: 1. Required components. 2. Optional components.

Answer: Must must, optional optional.

Customer replied: Still don't know.

He sighed: Alas, are the two words must and optional really so difficult to understand?

Customer replied: I understand.

Reading at night, I happened to see a cartoon.

A: The screen displays press any key to continue. What should I do?
B: Just any button.
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A: Why did the computer stop after pressing any key?
B: Which button did you press?
A: Press the POWER button easily.
B: ~~~~