Since verbs don't change for past or future tense, Chinese uses or context. Today: 我吃苹果 (I eat apples). Yesterday: 我昨天吃苹果 (I yesterday eat apples).
Words don't change based on their role (like "I" vs "me"). ⏳ Handling Time Chinese: An Essential Grammar
One of the best things about Chinese is what it have: Since verbs don't change for past or future