YOU SAID:

When I am preparing for JLPT N4 exam, X is the hardest thing for me to learn

INTO JAPANESE

JLPT N4 試験の準備をしているとき、X を学ぶのが最も難しいことです

BACK INTO ENGLISH

Learning X is the most difficult thing when preparing for the JLPT N4 exam

INTO JAPANESE

戦争の最大の困難だ

BACK INTO ENGLISH

That is the most difficult thing about war.

INTO JAPANESE

戦争の最大の困難だ

BACK INTO ENGLISH

That is the most difficult thing about war.