Answer:
1.when we're giving information or making observations.
2.when we'd like to check or confirm something.
3.Offering a choice of two.
Explanation:
1.We use falling intonation when we're giving information or making observations. We use falling intonation when we're asking information questions. (This distinguishes them from yes/no questions, which you can learn about about in Rising Intonation in American English.)
2.We use rising intonation when we'd like to check or confirm something. We use rising intonation to signal uncertainty or doubt. When we use rising intonation mid-sentence, it signals to the other person that we haven't completed our thought or idea, and suggests that they shouldn't interrupt us.
3.Mixed intonation in English sentences serve several functions including: Offering a choice of two (high to low intonation) e.g. black or white? Listing items (gradually rise then fall on the last word) e.g. milk, bread, butter and cheese.
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Hope it helps
