英语阅读,Dear Jack,We're going to have our school sports meeting

英语阅读,
Dear Jack,
We're going to have our school sports meeting on the playground next week.It will last three days from Thursday to Saturday.We have many competitions in running,such as 100-meter race,400-meter race and the ralay race.We also have the long jump,the high jump,and so on.I know you're good at running .Would you please take part in the boy's 400-meter relay race which starts at 10:30 a.m.on Friday?Please be on time,wear your sports shoes and take a bottle of water.
Good luck to you!
Yours,
Jim
1、What does Jim ask Jack to do and why?