人教版必修一补充阅读中的文章句子：

As a child, Tim studied French and Latin at school, but he found it difficult to be interested in just words and grammar rules. When he was 13, Tim started listening to Hebrew rap music. One day, he looked up the words in a dictionary and realized he could put them together to make sentences!

请问这里的“but he found it difficult to be interested in just words and grammar rules”，我的理解it不是指代不定式to be interested in...的，因为这样翻译不通，可不可以it指代前文学习法语和拉丁语这件事，而动词不定式表示“只通过……这种方式”呢？但是我不清楚这样一来不定式充当什么成分？方式状语吗？

另外还有没有类似的例子，即 sb find it adj to do sth.结构中，it并非形式宾语，不定式并非真正宾语的？