最近、日本人が英語を話す時に1番難しいのは個人的には発音だと思っています。まず、日本語にはない発音が多いのは１つの要素です。次に、文章内での強弱です。日本語はずっとフラットな発音で話すのですが、英語は強弱をつけないと伝わらないことが多いのでそこも難しいのだと思います。
Recently, I personally think that the most difficult thing for Japanese people when speaking English is pronunciation. First of all, one factor is that many pronunciations are not found in Japanese. Secondly, it is the strength and weakness within sentences. Japanese people speak with a much flatter pronunciation, but I think this is also difficult because English is often difficult to get across without using strong and weak sounds.