All the teachers found her a very clever girl .= All the teachers found she was a very clever girl .
区别：
前句是谓语found 之后跟宾语her 和宾补a very clever girl .
后句是谓语found 之后跟宾语从句she was a very clever girl .从句引导词that被省略.
译文：所有的老师都发现她是一个非常聪明的女孩.谢谢你希望帮到你。别忘记采纳啊~~