It’s not just what is said but how it’s articulated that shapes the meaning of human communication, and people use intonation to highlight the most important part of a sentence. Take, for instance, the sentence “Molly mailed a melon.” If someone asks, “Who mailed the melon?” people are most likely to stress “Molly mailed a melon.” If someone inquired what Molly did with the melon, it would be “Molly mailed a melon.” If the question was what Molly mailed, the response is “Molly mailed a melon.”