例句：

　　It has a clean and usable interface and has an Extensions API to extend and customize your installation.

　　它有一個(gè)清爽和可用的接口，并且還有一個(gè)擴展的API可以定制你的安裝。

　　Someone came out with a most useful suggestion.

　　有人提出了一個(gè)非常有益的建議。

　　Please cancel the words which are useless.

　　請把無(wú)用的詞劃掉。