Power network planning is a NP hard problem difficult to be solved.

电网规划是一个较难解决的NP难问题。

youdao

Not only is that problem very important, but it is very difficult to be solved.

那个问题不仅十分重要，而且还难于解决。

youdao

There are many Problems difficult to be solved in the information organizations in our country.

认为我国的情报机构，存在着许多难以解决的问题。

youdao

Difficult problems, which cannot otherwise be solved, are sent over to the court.

BBC: Syria: Islamist Nusra Front gives BBC exclusive interview