Read the text below.
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?