prep 2-80

80.   (28763-!-item-!-188;#058&004022)

Although at one time children's programming had been limited to a few hours a week, now, however, there are at least four cable networks that dedicate themselves entirely to shows produced specifically for children.

(A) Although at one time children's programming had been limited to a few hours a week, now, however, there are at least four cable networks that dedicate themselves

(B) With children's programming having been limited at one time to a few hours a week, now at least four cable networks have dedicated themselves

(C) Once limited to a few hours a week, there are now at least four cable networks with children's programming that dedicate themselves

(D) Children's programming was once limited to a few hours a week, but now there are at least four cable networks dedicated

(E) While children's programming had once been limited to a few hours a week, at least four cable networks are now dedicated

答案D, 请问为什么E错呢？另外，我感觉这道题目应该没有很明确的转折关系啊。用but是不是不太好？有点像OG里面museum那道题的感觉，请指教

请问E的后半句为什么要有连词连接呢？前面有while这个弱转折语气词已经可以连接两个句子了啊，就好比athough 句子A, 句子B

请指教，谢谢

不好意思，是我错拉，眼花拉没看到while

我认为E有2处错误：1。句子重心发生改变：将原句的强调部分cable networks 改为dedicated

                                 2。时态错误，once表示过去时

我觉得这两个错误不是很令人信服。呼唤nn出来解释一下。

In Longman DoCE:
once
3. at some time in the past, but not now
    Sonya and Ida had once been close friends.
    She and her husband had once owned a house like this.

E中关于dedicate的用法，我觉得也说得过去。
In Longman DoCE:
dedicated (adj)
    dedicated to
    The Woodland Trust is dedicated to preserving our native woodland.

Mami mami Hong，nn快出现。