Is it true or false? A sentence is a group of words expressing a complete though and each will begin with a capital letter.

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Somewhat ... it's incomplete though.

True. A sentence is a group of words that express a complete thought and each sentence should begin with a capital letter.

True. A sentence is a group of words that expresses a complete thought. In English grammar, sentences generally begin with a capital letter and end with a punctuation mark, such as a period, question mark, or exclamation mark. One way to determine if a group of words is a sentence is to check if it has a subject (who or what the sentence is about) and a predicate (what the subject is doing or being). Additionally, a sentence should convey a complete idea or message.