改为被动句:We must keep the noise under 50dbs here

改为被动句:We must keep the noise under 50dbs here Must we hand in the examination papers now 改为被动句顺便问下怎么将问句改为被动语态 把 We must obey the traffic ruies to avoid traffic accidents改为被动句 We must do the work right now（改为被动句） we must keep our classroom clean改被动语态 初中英语变为被动语态we must keep our classroom clean 将下列句子改为被动语态,英语.1Don't they tell you about it?2.Yesterday our teacher asked us to clean the classroom.3.we must keep the noise under 50dbs here. We must keep the air in the room clean.(改为被动语态）The air in the room must ＿＿ ＿＿ clean. we must keep happy同义句转换we must keep happy___is____ ____ keep happy 用被动语态把该句改为同义句We can do something to keep ourselves safe. We keep food cold in fridge.(改为被动语态） 主动语态改为被动语态,在什么情况下主动语态的主语被省略?eg:We must keep the noise under 45dbs hereg:We must keep the noise under 45dbs here(改为被动语态）The noise must be kept under 45 dbs here.为什么we被省略?什 We must water these young trees ofen.(改为被动语态) 改为被动语态：We must do the work right now We don’t permit you to smoke here.( 改为被动句) You must keep the door closed .( 改为同义句) You must keep the mobile phone off during the meeting.(改为被动语态） oceans we keep must the clean.怎么连词成句.