This is a paragraph that was inserted.

This is another paragraph whose first sentence was inserted at the same time as the paragraph above. This is a second sentence, which was there all along.
This is the first paragraph. This sentence was inserted.

This second paragraph was inserted.

This sentence was inserted too. This is the third paragraph in this example.

This is the first paragraph. This sentence was deleted.

This sentence was deleted too. That sentence needed a separate <del> element.