In Expressions^x, Auxiliaries^x, Pronouns^x

Another set of patterns occurred to me. These sometimes give learners trouble, and it's a good idea to practice them until they are automatic. They are drills on 'subject pronoun + auxiliary verb' contractions. Type X1: he's, she's, I'm, you're, we're, they're Type X2: he'll,...

Just change it into "I must go" - then it's easier to analyze: "go" here is the full verb that is in its infinitive and follows the modal auxiliary must - without to! I have to go: "have to" is the substitute form for "must", "go" again is the full verb in its infinitive. "Have to" here...