see之类的动词后面为什么接动词原形

When we have a word that already indicates the past tense or past experience, such as "seen," "watched," "heard," or "noticed," it is not necessary to use a different verb tense in the clause following it.

Using the base form of the verb (present tense) after these words is sufficient to convey the past experience or observation. The context and surrounding words will make it clear that the action occurred in the past.

It's important to note that this pattern applies specifically to these verbs indicating perception or observation. Other verbs may require different tenses depending on the specific context and intended meaning.