TTGWD3-26

Q26:

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.

1. the forming of bricks out of mud or clay, and, after some preliminary air drying or sun drying, they are laid
2. forming the mud or clay into bricks, and, after some preliminary air drying or sun drying, to lay them
3. having bricks formed from mud or clay, and, after some preliminary air drying or sun drying, they were laid
4. to form the mud or clay into bricks, and, after some preliminary air drying or sun drying, to lay them
5. that bricks were formed from mud or clay, which, after some preliminary air drying or sun drying, were laid

我选的是E，答案是D。其实D感觉挺好的，但是一看be to do结构就觉得是错的，哪位能解释一下？另外“be to do”是correctiveness错误还是effectiveness错误？

 看了原文，看到and,基本觉得是考平行对称，前后结构要一致，其实这样看来只有D对了， to form, and to lay， 当中的after..就是插入语拿掉看起来会比较简单。E中的which错了

be to do 好像不是书面语吧，在GMAT中比较常见的是to do is to do这种结构，是对的。其他的我觉得是effectiveness错误。

这个题吧，还是就想平行对称比较简单

what's wrong with " the method is to do A, to do B and to do C?

E is wrong at first sight with a glaring "which" stands out for nothing....

一看见be to do就兴奋，忽略了to do is to do结构。哎！断章取义了。谢谢指点。