首先use的現在分詞是using.word拼錯了,應該是world吧.
有點語法錯誤.動名詞是可以作主語.在你的句子當中.真正的主語是 to communicate with the outside world ,而不是using mobile phone.把that using去了,直接用by,這個句子就沒語法錯誤了.
It's convenient for them to communicate with the outside world by mobile phone.那這樣用呢？It's convenient for them to communicate with the outside world thatthe students use mobile phone.明顯是主語從句，to。。。在這里做目的狀語或者using mobile phone is convenient for them to communicate with the outside world。這兩種應該也都可以吧第一種顯得很累贅，而且語法又問題。第一個句子真正的主語依舊是to communicate with the outside world ，而不是that引導的那個句子。所以不可以用那樣的方式。第二個句子基本沒有語法錯誤，可是，them指代不明，不知道說的是誰，所以建議將them改為students會更好。using mobile phone is convenient for students to communicate with the outside world。這樣比較好。