_ the police arrived, the alien left the ground A:before,B: whenC:after,答案为什么选择before希望可以得到各位的帮助，答案为什么不是B和C

_ the police arrived,the alien left the ground A:before,B:whenC:after,选before麻烦各位回答具体点能不能从语法角度讲讲 When the police arrived,the man for 10 minutes. A traffic accident happened in the street.The police arrived() Before the police arrived,the alien left the shop.(为什么选择arrived而不用reach） help arrived in the shape of police officer是什么意思? _ the police arrived, the alien left the ground A:before,B: whenC:after,答案为什么选择before希望可以得到各位的帮助，答案为什么不是B和C 英语翻译1 这个将军命令他的手下英勇作战.The general commanded his men _ _ bravely .2 武装警察到达后就控制了局势.The armed police arrived and _ _ _ the situation.3 他被录用是因为他精通英语.He was employed beca The Smiths were looking for their lost child when the police arrived.改同义句___ the Smiths ____ _____ for their lost child,the police arrived Before the police arrived,the alien left the shop and then visited the Musrum of Flight whwn the police arrived the aline left the ground 为什么用when而不用while By the time the police arrived ,they (kidnap)the poor boy successfully yet. The victim's nose was ___(bleed) when the police arrived at the scene By the time the police arrived ,they (kidnap)the poor boy successfully yet. The police caught the thief yesterday.(改为被动语态)The thief__ _ __the police yesterday. When the police arrived ,the man for10 minutes A died B was diedChad di The (robbers,robber) ran away when the police arrived.选哪个? The murder _______(take) place when the police arrived.It's to late the police _（know） who he is