无效 (wú xiào): Not valid (Verb) — Meaning & Stroke Order

The court adjudicated that this contract is invalid.

Don't take antibiotics casually when you have a cold, because antibiotics are ineffective against viruses.

If these measures prove ineffective, what should we do next?

Formal contracts must be in written form; verbal agreements are invalid.

She first tried self-medication and only decided to seek treatment from a specialist after it proved ineffective.

He did not have the legal authorization to sign the contract on behalf of someone, so the agreement is invalid.

When communication failed, he ultimately resorted to social media to publicize the matter.

During the data cleaning phase, we must eliminate all outliers and invalid records.

Don't you think that solving problems with a slap is an extremely childish and ineffective way?