Is there a way to distinguish between "tin" and "knowledge" in Cantonese? It will make a joke. And "useless", "useless" and "death" How to divide "food"

Unless you deliberately distinguish between "tin" and "knowledge", generally speaking, most Cantonese speakers rarely notice the subtle differences in pronunciation of these two words, and rarely have the opportunity to use these two words at the same time, let alone have never heard of anyone joking about it.

"Shi" has two pronunciations in Cantonese, [si2] is a literary sound and [sai2] is a vulgar sound. Generally read more vulgar pronunciation [sai2].

"Death" is pronounced as [SEI 2] in most cases, and [Si 2] is a different pronunciation.

"Shi" has only one pronunciation in Cantonese. There is absolutely no polyphony.

Do you think you can explain the phonetic problems of Putonghua to a person who can't speak Putonghua or can't understand Putonghua Pinyin in written form or description?

If you want to distinguish, you should follow the audio and video of Cantonese Pinyin.