The best definition for the word juggernaut, as it is used in this excerpt from Kuangchi C. Chang's <em>Garden of My Childhood</em>, is the second one: <em>something large, powerful, and destructive.</em>
Explanation:
Juggernaut is a noun that describes a huge, powerful, and overwhelming force. In this case, this force, this character, this "<em>hero</em>" crossed the Yangtse "<em>as if it were a ditch;</em>". It refers to a powerful character capable of turning impossible into easy.
Sentences "I learned how to focus my camera" and "I also learned how to choose what to photograph" have identical subjects (I) and verbs (learned). Therefore, it would be better to combine them to improve the flow of the narrative: I learned how to focus my camera and also how to choose what to photograph.
