Form the perfect tense using the auxiliary verb 'haber' and a past participle. Irregular verbs in the perfect tense in Spanish The perfect tense is made of the verb 'haber' and a past participle.

Subject-verb agreement means that your verb must be conjugated, or changed, to fit (or agree) with the subject. Subjects can be singular or plural. Think of singular and plural as mathematical ...

For example, the tense may change between the methods section and the discussion section. The abstract is usually in the past tense due to it showing what has already been studied. Example: “This ...