Topic-Comment Sentences
When a noun or noun phrase has become established as a known element in a conversation, it can occur at the beginning of the sentence as the "topic," with the rest if the sentence functioning as a "comment" on it. This forms what is known as a "topic-comment sentence." In such a sentence, the object of the verb can be brought forward to serve as the topic of the sentence.
Ex) A: 你知道我的衬衫在哪儿吗?
B: 你的衬衫我给你妈妈了。
Ex) A: 你知道我的衬衫在哪儿吗?
B: 你的衬衫我给你妈妈了。