> For example, "uh-oh" has a high-low pitch. If you say it wrong it sounds very strange. "Uh-huh" to show understanding goes low-high. Again, if you reverse it it sounds unusual.

Wow… Thanks for making it clear that English also has tones! I hadn’t thought of it this way before. “Uh-huh” sounds similar to Mandarin tones 3 & 2. “Uh-oh” is similar to Cantonese tones 1 & 3.

I’m wondering if we can find good examples to teach the Mandarin tones. I think two or three syllable words are best because it illustrates the contour of the tones.