In contrast to large steel plants that take iron ore through all the steps needed to produce several different kinds of steel, processing steel scrap into a specialized group of products has enabled small mills to put capital into new technology and remain economically viable.
(A) processing steel scrap into a specialized group of products has enabled small mills to put capital into new technology and remain
(B) processing steel scrap into a specialized group of products has enabled small mills to put capital into new technology, remaining
(C) the processing of steel scrap into a specialized group of products has enabled small mills to put capital into new technology, remaining
(D) small mills, by processing steel scrap into a specialized group of products, have been able to put capital into new technology and remain(D)
(E) small mills, by processing steel scrap into a specialized group of products, have been able to put capital into new technology and remained
The contrast between large plants and small mills is logically phrased in choices D and E, but remained in E is not parallel with put. Choice D, the best answer, uses parallel verb forms to complete the construction have been able to put... and remain.
问题是这里为什么就不能是remained 和been平行呢?
small mills, ..., have been able to put capital into new technology and(have) remainedeconomically viable |