be after\be away\be all over\be back\be in\be on\be out\be up\ be up to\ 都是什么意思呀？"be"是不是跟着时态变化呀？she has gone into town ,but she hopes to( )soon.括号中为什么填“be back "?恳请指教！越详细越好！！

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两个相反意义的短语:进城与回来