It is such a difficult problem___nobody can work out.为什么要用as

It is such a difficult problem___nobody can work out.为什么要用as It is such a difficult problem___nobody can work out. It is such a hard work as we can't work out.这里用as是作work的定语从句 He is such a clever boy that he can work out many difficult This is so difficult a problem as no one can work out.as能不能换 It is such difficult work that we can't finish it in a shout It is (such) difficult work that we can't finish it in a sho 9. It is such a difficult problem _______ no one can work ou It is _question that i can't work it out.A.a so difficult B. he is such a lazy man_as__nobody can work with.为什么要填AS呢? The problen is difficult.I can't work it out. The problem is too difficult .------student can work it out