Sequent tenses refer to the relationship between verb tenses in a main clause and dependent clause. The verb tense in the main clause determines the tense used in the dependent clause. For example, if the main clause is in the present tense, the dependent clause can be in the present progressive, will/can/may + verb, past tense, or present perfect tense. If the main clause is in the past tense, the dependent clause can be in the past progressive, would/could/might + verb, or present tense. The document provides examples to illustrate these rules of sequent tenses.