A group of students from the US have been in China for a week． Here is part of their chat history（聊天记录）on WeChat．

（1）How much was Sunny's bill？

　　

（2）Did Stone find the bus stop in the end？

　　

（3）What are the group of students mainly talking about？

　　

（4）Do you think it is necessary for Sunny to give tips for the service？ Why or why not？