Final answer:
The correct answer is: He usually goes to school by bus. But today he went by train. The verbs agrees with the third-person singular subject in present and past tenses respectively.
Step-by-step explanation:
In the provided sentences, the subject and verb need to agree in both present and past tense. So, the correct verb forms for the sentences are: 'He usually goes to school by bus. But today he went by train.'
In the first sentence, 'goes' is the present tense form of the verb 'go', which agrees with the singular third-person subject 'he'. Similarly, in the second sentence, 'went' is the past tense form of 'go', denoting that the action has already occurred.
Learn more about Verb Conjugation