OG 129-问题悬而未决

129. In an effort to reduce their inventories, Italian vint­ners have cut prices; their wines have been priced to sell. and they are.

(A)  have been priced to sell, and they are

(B)  are priced to sell, and they have

(C)  are priced to sell, and they do （a)

(D)  are being priced to sell, and have

(E)   had been priced to sell, and they have

看了讨论，还是有些问题不懂。。再问

In choice C, the best answer, do is correctly used in place of the full verb do sell; in this verb, do is a conjugated form and sell is in the infinitive form, corresponding to its previous use in the sentence (in the phrase priced to sell),1。到底省略了什么？2。时态平行，为什么不可以选A,have cut 和 have been priced对称