When he arrived at the hospital,he asked worriedly who was(operate)____on.为什么答案是 being operated 句子那个成分看出用这个答案

Is Mr.Morrison in his office now?I have a question for himsoory,I don't know ,When __(got to ,had reached,arrived,had arrived at ) his office ,he was not there IT was snowing when he arrived at the station是什么从句 ti was snowing when he arrived at the station是什么从句 英语翻译1.We were leaving the office when the telephone rang.2.It wasn't snowing when he arrived here at 8 o'clock yesterday evening.3.Were you writing him a letter just now? when he( )the palace,he was very surprisedA.left for B.arrived on C.arrived at D.got away原因写清 When he arrived at the a___ ,he was just in time to see the plane t___ off. He,out,when,he,of,arrived,the,breath,at,top,of,hill,was,the连词成句 he,out,when,he,of,arrived,the,breath,at,top,of,hill,was,the(连词成句） he out when he of arrived the breath at top of hill was the 怎么组成一句话, 吧when he arrived at the hotel,he found the guest had gone的前半句用分词替换掉 He was sleeping late when it arrived _______,his friends met him at the station.A.arriving in Chicago B.Arrived in Chicago C.On arriving in Chicago D.When he arrived in Chicago 13.It was midnight ____ he arrived home.A.that B.when C.which D.at which when he british first arrived at the new land ,they felt very far from english speakers back home.back home he left the room when I __________.A.got B.arrived at C.reached D.got to he arrived home at seven o'clock.（at seven o'clock划线）为什么用when划线部分提问,为什么用疑问副词 when he promised to pike me up at the school gate .however he __yeta didn't arrive b doesn't arrive c isn't arriving d hasn't arrived He promised to pick me up at the shcool gate .however ,he ----- yet.A.Didn't arriveB.Doesn't arrive c.Isn't arriving D.Hasn't arrived .