Final answer:
The auxiliary verb for present perfect tense is 'have' or 'has', depending on the subject.
Step-by-step explanation:
The auxiliary verb used for forming the present perfect tense is 'have' or 'has'. For instance, in a sentence like 'The historian Eduardo Galeano has argued that...', the auxiliary 'has' accompanies the past participle 'argued', together creating the present perfect construction.
The choice between 'have' and 'has' depends on the subject; 'have' is used with the pronouns 'I', 'you', 'we', 'they', and plural nouns, while 'has' is used with 'he', 'she', 'it', and singular nouns.
The auxiliary verb for present perfect is 'have' or 'has'.
For example: 'She has finished her homework.'
In this sentence, 'has' is the auxiliary verb and 'finished' is the main verb.