用英语翻译：你们要集中精力学习。句中用到（be focused on）。另外为什么focused,要加ed？

with his eyes focused on中为什么要用focused,而不是用focusing be focused on是focused on的被动语态么? be focused 请问All eyes were focused on him 为什么要用被动? be focused on这里的focused是被动语态吗? He sat there,with his mind focused on his work中为什么用focused不用 是focus on还是be focused on be focused on=be____ to 英语翻译backward focused 英语翻译With operations focused on key customer markets,we drive 英语翻译Responsibilities:- Heavily focused on media relations,it 英语翻译Although attention has been focused mainly on the phosph