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.
11. 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. (A) the forming of bricks out of mud or clay, and, after some preliminary air drying or sun drying, they are laid (B) forming the mud or clay into bricks, and, after some preliminary air drying or sun drying, to lay them (C) having bricks formed from mud or clay, and, after some preliminary air drying or sun drying, they were laid (D) to form the mud or clay into bricks, and, after some preliminary air drying or sun drying, to lay them (E) that bricks were formed from mud or clay, which, after some preliminary air drying or sun drying, were laid Parallelism; Verb form The purpose of the sentence is to describe the historically most popular method of building walls. The first clause announces this topic and the second clause describes the particular method. The clearest, most efficient way to accomplish these two pieces of business is to use a parallel structure. The ways to build in the first clause is narrowed to the single way to form and to lay in the second clause. There is no need to alternate the verb phrases between active and passive voice or to shift tenses. 为什么to way 决定了to form和to lay? 求解~~