Hi Phucuong; Welcome to English Forums. Your questions is about the past perfect tense. This tense is used when there are two times in the past, one earlier than the other.
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phucuong5415Thank you, I kinda understand now ^.^It is not simple, and it takes some practice.
phucuong5415differences'had cycled' is the past perfect. Take a look at this post and follow the link there to another post. These may help you.