【答案解析】[参考范文]


I am sorry to say that I can no longer go with you for the trip to Shanghai.
I told you that I would go to that city because there are many interesting attractions for me to visit. But I would have to attend the national examination for an accountancy certificate. This is very important to me. I want to improve my financial status and social position. Please accept my apologies.
Enjoy your trip.