This is difficult.
This is difficult.
It's possible but highly challenging.
I'm not sure if I'll be able to do this.
That was very difficult.
That is not particularly difficult.
それは難しいね。
That is difficult.
それは難しいね。
それは難しいね。
That is where the difficulty lies.
That was difficult.
That will gradually become more difficult.
This is difficult.
難しいわ。