og11-49，新问题

(A)            programs that enable a family with insufficient savings for a conventional down payment to be able to move into new housing and to apply

(B)            programs that enable a family with insufficient savings for a conventional down payment to move into new housing and to apply

(C)           programs; that enables a family with insufficient savings for a conventional down payment to move into new housing, to apply

(D)           programs, which enables a family with insufficient savings for a conventional down
            payment to move into new housing, applying

(E)            programs, which enable a family with insufficient savings for a conventional down payment to be able to move into new housing, applying

Rhetorical construction

In a lengthy sentence consisting of many phrases, it is essential to determine which phrases and words are necessary to the sentence and which words may be eliminated because they are unnecessary The relative pronoun that correctly refers to programs and introduces the subordinate clause; family is followed by two phrases that are clear and correct. To be able to move, however, is needlessly wordy, repeating the meaning of enable, and can be reduced to to move. This creates a parallel construction in which programs ... enable a family ... to move ... and to apply.

A          To be able to move is wordy; to apply is not logically parallel to the infinitive phrase (able) to move

B          Correct. In this sentence, eliminating the wordy construction to be able allows to move to be parallel to to apply.

C          Using a semicolon here causes that to refer too broadly to the entire previous clause rather than specifically to programs; the two infinitives should be joined by the conjunction and, not separated by a comma

题目解释，首先，用“To be able to ”显得多余；

其次，如果一定要用的话，为了对称，这里应写成“enbale X to be able to do Y and be able to do Z”(省略to)

如果没有enbale，则应写成“X is able to do Y and do Z”

谢谢回复。

解释的第一句话应该是说to be able to多余的。第二句话（红色）似乎是说be able to的省略不对。

我想知道的是当be able to充当两个并列成分的共同谓语时候，第二个该如何选择？

在网上找到http://wy.yuloo.com/wy-ielts/yude/2006-12-26/33862.html，有一句话

6. It is quite unnerving not to be able to see or to establish contact with the other person,even though we have learnt to have conversations with people we cannot see,as on the telephone.

译文 即使我们适应了像打一样在互相看不见的情况下谈话，这种看不见或接触不到对方的谈话也会使人感到很不自在。

这里省略的是 be able，而不是be able to。

而og的解释，似乎是要省略be，前后都有able to。

再顶一下

楼主可能误解了OG的解释，那句话只是说to apply
    和to be able to move 不对称，并没有探讨“be able to充当两个并列成分”的应该如何

上面这个例句，因为前面有unnerving not to ，所以后半部分省略了to (be able to) establish
  

至于“be able to充当两个并列成分”时，比方说，Tom was able to eat 20 hamburgers and to drink 10 bottles of cola when he was 15.

补充：根据OG11Verbal第44题，“be able to充当两个并列成分”时，应为：X is able to do Y and（to） do Z”, 后半部分的to 可省略