parents found it is difficult/it difficult/it was difficult to teach children.说明选择原因
问题描述：
parents found it is difficult/it difficult/it was difficult to teach children.说明选择原因
答
Parents found it difficult to teach children.
此处可以看成是find + obj.+ adj.（PS：后面可以跟to do,也可以加doing）
如果把它看成是一个同位语从句的话,可以这样写：
Parents found that it was difficult to teach children.
这就是一个find + that从句了
供参考!