检查员们难以发现哪些文件重要，哪些不重要。

It was difficult for the inspectors to discover which documents were important and which were not.

《柯林斯英汉双解大词典》

这种狼行踪隐秘，难以发现。

The wolf is cryptic and difficult to spot.

youdao

他们设计制造了一种仪器，用来帮助寻找那些难以发现的裂缝。

They designed and built a device that helps find those hard-to-see cracks.

youdao

What you find when you actually open up Pynchon's novels is an incredibly rich world of human detritus, of history.

当你真正看Pynchon的书,你能够发现一个难以置信的。

耶鲁公开课 - 1945年后的美国小说课程节选

and you're looking to the menu and there are so many delicious things that she cannot seem to make up her mind.

你们看菜单时，发现有太多美味的菜肴，你的女友一时难以取舍。

I need 课堂 - SpeakingMax英语口语达人