—Do you haveany idea what Paul does all day?

—As I know, hespends at least as much time playing as he _______.

A. writes  B. does writing     C. iswriting      D. does write

这是省略，补全句子您可能就明白了：

As I know, he spends at least as much timewatching TV as he spends time writing. 据我所知，他花在看电视的时间至少和花在写作的时间一样多。

这里为避免重复，用does代替spends, writing与上文的playing相对。

我们还可这样改写句子：

As I know, he spends at least as much timewatching TV as he spends time writing.

= As I know, the time he spends playing is atleast as much as that he spends writing.

这就更容易看出上下文逻辑关系了。