A parenthetical element is defined as a word or group of words that interrupts the flow of a sentence and adds additional information to that sentence, however not important in the sentence. The sentences that apply are A, B and D.
The statement that is not true about parenthetical elements is B, which claims that only one comma is needed when a parenthetical appears in the middle of a sentence. In reality, two commas are required to correctly set off a parenthetical element. Parenthetical elements provide additional details but are not crucial for the sentence's overall meaning.
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