I spent two hours on this maths problem这句话里on this maths pro

I spent two hours on this maths problem这句话里on this maths pro I spent two hours on this maths problem. this maths problem is_________that one. I spent two hours working out this problem.(改为同义句) This maths problem is____________ and I can do it___________ I always got an A on maths tests ( )this year .Ain B on C/ he spent two hours -- this book.A.in read B.on reading C.in __ __ THIS MATHS PROBLEM IS ! This maths problem is ___ that one . this maths problem.为什么加s It is difficult () out this maths problem This maths problem is easy to work out.同义句This maths problem