难以 + Verb
The adverb 难以 (nányǐ) means 'difficult to' or 'hard to.' It is placed before a verb to indicate that the action is very hard to accomplish. It is more formal than 很难 and often appears in written Chinese, such as 难以处理 (difficult to handle).
这道数学题难以在短时间内解出来。
Zhè dào shùxué tí nányǐ zài duǎn shíjiān nèi jiě chūlái.
This math problem is difficult to solve in a short time.
他的行为难以理解。
Tā de xíngwéi nányǐ lǐjiě.
His behavior is hard to understand.
这种损失难以用金钱来衡量。
Zhè zhǒng sǔnshī nányǐ yòng jīnqián lái héngliáng.
This kind of loss is hard to measure in terms of money.