Dear Tom,
Thank you for your invitation.I'm sorry i can' t visit your family's farm.I am really busy this weekend. This evening i have to visit my grandparents. And on Saturday i have to help my dad in the garden. On saturday afternoon I 'm going shopping with my mom.I like shopping.On Sunday I have to study for my Chinese test .This time I really want to get a good grade.And on Sunday evening .I'm going to the concert with my frends.
Maybe next time .Please write me soon.
Yours,
John
我们也才上完这个单元。希望你能采纳。