a confederation between two states的用法和样例：
- A checkmark menu item is vastly preferable to a flip-flop menu item that alternates between two states, always showing the one currently not chosen.
- Our fight against Chiang Kai-shek had become a war between two states,between two great armies.
- Some people may even start to ask why the Albanian nation should be split between two states.
- Perhaps existing two arcs above in the same direction between two states, adjacency matrix could only record one of them.