第四, 同位语从句。 Eg: It is an undeniable fact that environmental pollution becomes increasingly serious. # g; [! \& |( S0 q6 X J 环境污染变得越来越严重是不可否认的事实。 8 b: L- L& {( R$ y/ K Eg: No one can deny the basic fact that it is impossible for average workers to master those high-technology skills easily. % z# @* V6 x) ~. q2 j, b6 }* ^ 没有人能否认这一基本事实:对于一般工人来讲,轻松掌握这些技术是不可能的。