I'm sure she's keeping something back from us.

　　我肯定她有什么事瞞著我們。

　　Some teachers find it difficult to keep their classes in order.

　　有些教師覺(jué)得難以維持課堂秩序。

　　Keep down! You mustn't let anyone see you.

　　蹲下！一定不要讓人看見(jiàn)你。

　　I keep thinking back to the day I arrived here.

　　我不斷回想起剛到這兒那一天的情景。

　　Keep that dog out of my study!

　　別讓那狗進(jìn)我的書(shū)房！