How can you tell that the second syllable in belief is stressed?

You can tell the second syllable in "belief" is stressed because of the following:

* Pronunciation: When we say "belief," the sound of the second syllable, "lie," is longer and stronger than the first syllable, "be."

* Meaning: In English, stress often falls on the syllable that is most important for the word's meaning. In "belief," the "lie" syllable carries the core meaning of the concept of belief.

* Dictionary: Dictionaries will often indicate stress by using an accent mark over the stressed syllable, like "belief".

Overall, the stress pattern in "belief" is a common one in English, and it's easy to recognize by listening to the pronunciation and considering the meaning of the word.