That problem is the most difficult ---- all用of 还是among答案上是among是不是答案错了那为什么不能用OF呢

the problem now is that i have lots of problem【】 to ask是problem还是problems 翻译It is high time that we solved the problem This is the problem that I confront.对么? That is how to solve the problem.(改为同义句) That is how the problem ( )( ).一括号一词.紧急! so I know everyone here.That's the problem-the problem is that there's nothing to do 错哪? what is the problem meaning:the problem is that there is nowhere that he wanted to go for his holiday. it is a problem that One problem with the discussion is that I haven't ...One problem with the discussion is that I haven't decided too much about the infrastructure. The head teacher's ______ problem is that he is _______ busy. loving you has never been the problem .what is troubling me is that loving The problem is _______ he is too tired.A.which B.when C.what D.that Today the human have a big problem needs to be solved.That is environment problem.Our environment is work problem finish the can‘t the i that连词成句 That is the new ( ) of working out the problem.填一单词 Is this problem （ ）the teacher explained yesterday?A、that B、the one It is hoped that the two countries will settle the problem in a peaceful way. difficult as the problem is