You can’t always tell if a person is being polite based on their words alone. Often, a person’s intonation and stress will be the key to what they mean. For example, a person being impolite will sometimes put stress on certain words to suggest that they don’t mean what they say.
Listen to two recordings of the same phrases with very different stress and intonation. Which one do you think is polite?
Example #1: “Yeah, that’s a great idea.” is polite.
Now, listen to different recordings of the same sentences. The first one is taken from the recorded dialogue and would be considered more polite. The second one was recorded separately, and would be considered impolite. Think about what intonation or stress markers make each recording polite or impolite.
Listen carefully and remember : the first recording of the sentence you hear is polite. The second recording of the same sentence is impolite.