Chinese frequently moves a noun phrase to the front of a sentence to serve as the topic, leaving a gap in the clause where it would normally appear. This topic-comment structure is one of the most characteristic features of Chinese syntax. For example, 这本书我已经看过了 means "this book, I have already read (it)."
这件衣服我穿着太大了。
Zhè jiàn yīfu wǒ chuān zhe tài dà le.
This piece of clothing is too big on me.
那部电影我看过两遍了。
Nà bù diànyǐng wǒ kàn guò liǎng biàn le.
I've already watched that movie twice.
中文我觉得声调最难。
Zhōngwén wǒ juéde shēngdiào zuì nán.
With Chinese, I find the tones the hardest.