英文比較級文法

我們的河流不再像以往那麼潔淨了。
(a) Our rivers are not as clean as they are before.
(b) Our rivers are no longer as clean as they were used to.
(c) Our rivers are not as clean as they used to any more.
(d) Our rivers are no longer as clean as they used to be.

解答是(D)
我怎麼看都覺得4句都可以用
可以幫我把每個選項的文法錯誤舉出來嗎?

感恩~
更新: 請問選項(b)的 no longer 跟not longer 不同嗎?
2 個解答 2