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You will need some knowledge of English intonation patterns if you are to understand English grammar more fully. This is because features of intonation are important for signalling grammatical distinctions, such as that between statements and questions. For example, a sentence like They are leaving can be a statement when said with falling intonation, but a question with rising intonation.

LEECH, G.; SVARTVIK, J., 2012, p. 33.

What is the importance of the intonation for speaking english?