That was a difficult question, but Mary still __ to work it

That was a difficult question, but Mary still __ to work it It was ()that Mary couldn't do it alone.Aso difficult a work it was difficult __ the railroad at that time.a.built b.to b It was a little difficult,but I still finished it by I went to bod early last night,but it was still difficult fo So difficult __ it to work out the problem that I decided to i know that it is very difficult to stop smoking ,but you __ i know it is i( ) difficult to run a marathon ,but i still w she thought that the work was too difficult to do it It was still a question _____ man can go to the moon. “It is difficult to answer that question” means _______ . Miss Gao asked a question,but it was ______ that nobody coul