RE: Is the human blood green in colour besides being red?

You might want to revisit the notion that 20-30% plagiarized content is acceptable to anyone, @cyprianj.

From the Editage Insights website -

Q: What is the acceptable percentage of plagiarism [in a] report?

Answer: There is a lack of consensus or clear-cut-rules on what percentage of plagiarism is acceptable in a manuscript. Going by the convention, usually a text similarity below 15% is acceptable by the journals and a similarity of >25% is considered as high percentage of plagiarism.

But even in case of 15% similarity, if the matching text is one continuous block of borrowed material, it will be considered as plagiarized text of significant concern. On the other hand, text similarity due to the usage of common terminologies and method related details in ‘Methodology’ part of a manuscript should not raise a serious ethical concern.

And to be clear, "usage of common terminologies" certainly doesn't cover taking entire sentences verbatim, or even slightly rewording to make them harder to detect by plag checkers seem original.