英语初学者,求纠错Grant comes back to school after being absent for a

英语初学者,求纠错
Grant comes back to school after being absent for a week.His friend Mike,greets him happily as soon as he enters the classroom."Hay,Grant,long time no see!" Mike says."I am glad to be back Did I miss a lot of lessons?" Grant says."Yes,but I am sure you will catch up soon",Mike answers,"Thank you" Grant says.

Question:
Why does Mike greet Grant happily?为什么Mike高兴地和Grant打招呼?
Answer:Because Grant had been absent for a week and has just been back to school.请帮忙看看回答有没有错误,