“Singora, you are lovelier than the heroines ofancient times!" he cried, with what he thought was his most winningsmile.-- from one fiction.
谢谢各位老师的解答，想请教一下！上面句子中的 with是介词，后面可以加完整的句子吗？我在阅读简写版英文书本的时候常常有遇见介词后面加完整的句子。
我一直的理解是介词后面是只能加名词或则代词（before 或after引导的从句除外）
好问题！你提到的这类型似的句子还不少，在小说中非常容易见到。我说一下我的怎么看，可能不正确，算是给出一个理解的思路。
“Singora, you are lovelier than the heroines of ancient times!" he cried, with what he thought was his most winning smile.（书名为“Barchester Towers”）
可以把he thought 理解为插入语，直接拿掉后变为“with what was his most winning smile”（名词从句）。with后面接的还是某种smile。如此讲解就通了。
这里还有一个问题我提一下，就是为何是“with what was his most winning smile”而不是““with what his most winning smile was”？这涉及到不一样的词序表示的意义略有不同。由于有he thought的存在，所以用“with what was his most winning smile”是比较合适的，表示的是分类：“他以为的最能代表他胜利的微笑的那种微笑”，而不是其他的某种微笑。
The New Cambridge English Course 3 Practice Book with Key这本书的第76页有这么一句：
With what he thought was tremendous presence of mind , he pulled on to the hard shoulder , stood up on the front seat and urinated into the flames.
再列举一些小说中的类似例子：
He'd been thinking about this all afternoon, had in fact thought of nothing else, and he'd come up with what he thought was the most logical solution.（Baby With A Badge）
He was all too familiar with what he thought was one of the side effects of her wounds.
He came up with what he thought was a good idea.
He approached the woods with what he thought was an unwarranted trepidation.
