顺便想问一下，这题：There are several ways to build solid walls using just mud or clay, but the most extensively used method has been the forming of bricks out of mud or clay, and, after some preliminary air drying or sun drying, they are laid in the wall in mud mortar.大家觉得 the forming of bricks out of mud or clay, and, after some preliminary air drying or sun drying, they are 中，的the forming（ of bricks ）是不是算作是修饰语？如果可以，那they are ....是不是可以理解为“代词不指代做定语的名词“所以they 没有指代对象。。恩，