In this example the past participle EXPERIENCED (from the bare experience) is used in a present perfect simple tense. This means that the writer is talking about a past experience without mentioning a time reference.
For regular verbs, adding -ed to the base form creates the past participle. For the present participle, add -ing to thr base form.
For perfect participle write having and the verb in the past participle .
"Suddenly the evidence overwhelmed me: there was no longer any reason to live, any reason to fight" and "Father! Father! Wake up. They're going to throw you outside."
