Sentence examples for a difficult thing to answer from inspiring English sources

I think that's a difficult thing to answer.

"It's a difficult thing to do.

"That's a difficult thing to do.

It was a difficult thing to do.

It is a difficult thing to do.

It's a hard thing to answer.

Medicine is a difficult thing to learn.

That's a difficult thing to say.

It is a difficult thing to achieve.

Evil is a difficult thing to eliminate".

Hope is a difficult thing to kill.