Causatives are used when one person causes another to do something. The verbs used as auxiliary verbs for causative sentences are "have" and "get”. The tense of the sentence is shown in the auxiliary verb and the main verb of the sentence is usually the base form, or the infinitive without “to”. (That is to say, the infinitive of “run” is “to run”, but in a causative sentence, you’d just use “run”. Here’s a couple of examples: Present causative: She has him clean his room every day. Here, the auxiliary verb is “has” and it’s in the present tense. What she has him do is “clean”. This one looks like a present tense verb, but it’s the base form of the verb “to clean”. Past causative: He had his assistant correct his students’ papers. This one follows the format, but I want to give you one in which the base verb is not used, but the infinitive is. She got her husband to take out the trash. Here, “got” is our causative and “to take out” is the verb. It’s a phrasal verb. Got it? If not, ask for clarification. I’ll do my best to give you a clear answer.