Last night, he / be/very busy/, but he/ help / his younger sister / her homework. →

A. Last night, he was very busy, but he helped his younger sister with her homeworkB. Last night, he is very busy, but he helped his younger sister with her homeworkC. Last night, he were very busy, but he helped his younger sister with her homeworkD. Last night, he are very busy, but he helped his younger sister with her homework

Đáp án đúng là: A