发音难掌握The pronunciation is difficult to master.
词语难理解、难记The words are difficult to understand and difficult to remember.
语法难理解Grammar is difficult to understand.
汉字难写、难记Chinese characters are difficult to write and remember.
汉语难听懂When listen Chinese is difficult to understand.
汉语难表达It is difficult to express in Chinese.
缺乏练习口语的机会Lack of opportunities to practice spoken Chinese.
其它,请补充:Others, please add: