It is difficult to master two different languages.
He is difficult to get along with.
王牌句型：It is difficult（for sb.） to…
It is difficult for me to drive a car.
It is difficult to learn Japanese well.
It is difficult to figure out what he really means.
Nothing in the world is difficult for one who sets his mind on it.
All things are difficult before they are easy.
difficulty n. 困难，艰难；难事；困境
This question is full of difficulties.
Do you have any difficulty with English?
王牌句型： have difficulty in + V-ing
We had a little difficulty in finding your office.
I always have difficulty in pronouncing new words.
Do you have any difficulty in working with others?
There won’t be any difficulty in finding a replacement.