在下面对话的空白处填入适当的话语（话语可以是词、短语或句子），使对话完整．
A：Hi，John．Are you free this Sunday？
B：Yes．（51） ？
A：I'm going to plant flowers in the city park．（52） ？
B：Sure，I'd love to．Everyone should play a part in making our city beautiful．
A：That's right．
B：（53） ？
A：We're going there by taxi．
B：But I think taking a taxi costs too much，How about taking a bus？
A：（54） ．Then let's meet at the bus stop on Sunday morning．
B：OK．（55） ！
A：See you!