How to find a main idea? i'm having trouble so maybe you can give me tips.

Choose the pronoun that can replace the underlined word(s) in each sentence. mr. ruiz gave the students some homework.answer "them" the check arrived in the mail today.choose the pronoun that can replace the underlined word(s) in each sentence. mr. ruiz gave the students some homework. answer "them" the check arrived in the mail today."it" devon is saving money so that devon can buy a new video game."he" everyone is excited that anyone’s name could be drawn in the raffle. "his or her"