Both tenses refer to the past, but they differ based on whether a specific time is mentioned and whether there is a connection to the present:
- Past Simple: The action ended at a definite time in the past and has no relevance to the present.
- Present Perfect: No specific time is mentioned; it emphasizes the impact on or experience related to the present.
我I 看saw 他him 昨天yesterday.
I saw him yesterday. (Definite time → Past Simple)
我I (完成时)have 看seen 那部that 电影film.
I have seen that movie. (Experience, no specific time mentioned → Present Perfect)
Note: Once definite past time markers such as yesterday, last week, in 2019, or ago appear, use the Past Simple, not the Present Perfect.

两个时态都讲过去,区别在于是否说具体时间、是否和现在有关:
- 一般过去时 (past simple):动作在确定的过去时间结束,和现在无关。
- 现在完成时 (present perfect):不说具体时间,强调对现在的影响或经验。
我I 看saw 他him 昨天yesterday.
我昨天见过他。(确定时间 → 一般过去时)
我I (完成时)have 看seen 那部that 电影film.
我看过那部电影。(经验,没说何时 → 现在完成时)
注意 一旦出现 yesterday、last week、in 2019、ago 等确定过去时间,就用一般过去时,不用完成时。