build soild walls~~

[little mice]

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

OA： D

my confusion: why form and lay should be parallel with to build? I understand that the first two must be parallel with each other, but why they should be with"to build" ?

[Ben.Miller@ApexGMAT]

Excellent question.

Verbs need to be either in agreement, or in a tense progression in the case of telling a story. eg She worked a full shift, and then came home and ate a sandwich.

In this problem, we begin in the present (are) and (to build) is used as an infinitive. We then shift backward to refer to the past (used) which then must be paralleled tense-wise. The crucial part ISN'T paralleling with the infinitive up top, but paralleling with the other verb (are laid), since its part of the same time/process being described.

Finally, (the forming) is a gerund, which is technically a noun. But (has been...) must be followed by a verb. On the other side, the verb that follows (has been...) has to agree with the tense if (are laid). D is the only answer that fulfills all these requirements.

As an exercise, pick through the other incorrect answers and find the inconsistencies. This will build your attentiveness to tense subtleties within SC problems.

Ben

[Fdambro294]

“Used” is a tensed verb?

Are you sure it isn’t a Past Participle? (I.e., an intended verb)

Not the greatest explanation….