I her at school already. a) saw ; b) have

I have seen her at school already. Я теснее лицезрел ее в школе.

The sentence is in Present Perfect. Present Perfect is used for action that took place in the past but the result of the action connects with the present. Present Perfect is formed with the help of the auxiliary verb to have and the third form of the verb. Have / has (the third person singular) + verb +ed / the third form of irregular verbs.

Negative is formed with not which stands after the auxiliary.

Have / has + not + the third form of the verb.

Interrogative Auxiliary + subject + the third form of the verb.