How to distinguish between open syllables and closed syllables in polysyllables? Thank you for your advice.

First, a polysyllabic word should be divided into syllables. Traditionally, it should be divided from phonetic symbols. This is defined by phoneticians. For ordinary English learners, there is no need to worry about how syllables are divided. Generally speaking, however, larger dictionaries, such as American traditional dictionaries, will also divide syllables from the perspective of words, and understanding the pronunciation of vowels and consonants in open syllables and closed syllables will help to remember words. As follows:

Basketball, basketball can be divided into three syllables. The so-called open syllable or closed syllable. It is defined from the perspective of letter combination of each syllable. Bas closed syllable, ket closed syllable and ball are also closed syllables.