What is the grammatical outline of 你英语说得很好
This is very common in Chinese/Mandarin: Re-/Pre- position the object.
1: to emphasize object while subject is omitted (understood).  I call this fake subject: 北京到了。 Beijing can not &quot;arrive&quot;.  &quot;We&quot; arrive at Beijing.
2: subject unknown:  前面来了一辆车。Car doesn't &quot;come&quot;, somebody drives it to come.  There is alternative: 有人开了一辆车从前面来了。 which is not as neat as first one. &quot;shorter and to the point&quot; is always the trend of languages.
3: subject unknown but unique to Chinese (not polite to use &quot;someone&quot; as the implication is small potato): &quot;得&quot; complement 这个鱼烧得不错。vs 有人烧这个鱼烧得不错。 Chef or some housewife is not just &quot;有人&quot;.
4: similar with &quot;得&quot; complement but subject known (like 1, emphasizing object): 他说汉语说得很好。 vs 他汉语说得很好。 not just neat，you even save repeating the verb.
5 subject known or unknown, the object is a long and complicated phrase:  昨天我刚从上海买回来的新书今天早上在学校弄丢了。 alternative: use &quot;被“ but not as neat and also subject must be known.
6 the most special one is that I want to emphasize both the subject and the object at the same time and it's not &quot;得&quot; complement:  original: 今天早上在学校他弄丢了我昨天刚从上海买回来的新书。 --&gt; weird: 今天早上在学校他我昨天刚从上海买回来的新书弄丢了。 Ah, the wisdom of Chinese: solution &quot;把”  今天早上在学校他把我昨天刚从上海买回来的新书弄丢了。 Perfect:  It's &quot;he&quot; and it's &quot;my new book&quot;, both emphasized in equal way.
As I like to believe: language is &quot;alive&quot;.  It evolves and mutates daily.  Grammar must do the same to follow, but looks like it will never catch up.  Why must find grammatical explanation for all the expressions used and understood?