Top 3. Because even looking up a word in the dictionary is complicated.
One of the most unreasonably difficult things about learning Chinese is that merely learning how to look up a word in the dictionary is about the equivalent of an entire semester of secretarial school. Chinese must also be one of the most dictionary-intensive languages on earth for there are various dictionaries.

原因三：即使在字典中查漢字也是非常復雜。
學習漢語最莫名其妙的困難之一，就是即使僅僅學會怎么查字典，也要耗費一個秘書學校整個學期的學習時間。漢語一定是地球上最精于運用字典的語言了，因為各種各樣的字典實在太多。