地点介词 in / on / to + 地点 — 英语填空题
题目
暑假旅行计划：Lily and her family are going to travel. They will stay ___ Beijing for three days, and then they will go ___ Chengdu by train. On the train, they will sit ___ the train for about ten hours. 填入合适的介词（按顺序填三个词，用逗号隔开）