この数学の問題は難しくて、一時間考えても解けなかった。
This math problem was so difficult that I couldn't solve it even after thinking for an hour.
日本語の敬語は外国人にとって難しい。
Japanese honorific language is difficult for foreigners.
今の成績では第一志望の大学に合格するのは難しいだろう。
With your current grades, it will probably be hard to get into your first-choice university.
試験は思ったほど難しくなかった。
The exam wasn't as hard as I had expected.