Ate is the simple past of the verb to eat, whereas eaten is the past participle. As you are using the auxiliary have for the present perfect, you are bound to use the past participle. The simple past form is to be used independently for finished actions or situations.Mar 15, 2013 read more
The past tense of eat is ate. The third-person singular simple present indicative form of eat is eats. The present participle of eat is eating. The past participle of eat is eaten. read more