I worked on the problem for a long time and I worked it out

I worked on the problem for a long time and I worked it out I worked on the problem ____ a long time and I worked it out I worked out the problem so( )(easy) 英语翻译Well,I worked in business for a long time and so I under I don't understand the way_____they worked out the problem. I don`t understand the way ___they worked out the problem A. The problem is too hard.I haven't ( )the answer A.WORKED ON I have worked out the plan and I must put it into pratice 帮我 The problem is difficult,（ ）he has worked it out. with the teacher‘s help,i worked out the math problem(同义句) The problem is difficult,____,he has worked it out.A:though the problem is very difficult,but he worked it out ____ a la