难解决的

This treating method can remove the sulfur and incerase the percent of iron and resolve the trouble that pyrite cinder is difficult to desulfurate.

该方法能很好地除烧中的并富集其中的铁,解决了多年来一直困扰着人们的酸难的题。

A three-legged ejector sleeve is adopted in the die casting mould to take cast stripping mould, the problem that the cast difficultly demould is solved.

采推管推出铸件，解决了轴套铸件模难的题。