serve as 与 be served as?

serve as 与 be served as? be served as有这样的说法吗还是只有serve as house be serve as serve Environmental concerns served as one of the main reaso serve and be served是什么意思? Not to be served,but to Serve serve as beds for serve as与serve for表达的意思一样吗?能互用吗? serve as a great motivation 跪求英语演讲稿,serve,not to be served can be filled and served as a sweet snack or made plain and as.as it can be 与 as.as can be 有什么区别呢?