Upon arriving home,I was surprised to find the paper I had had ___ was missing.这里的upon arriving是什么用法?

Upon arriving home,I was surprised to find the paper I had had ___ was missing.这里的upon arriving是什么用法? Upon arriving home,I was surprised to find the paper I had had ___ was missing.为什么选prepared的形式啊 when arriving home和when I arrived home 的区别 Upon arriving home,I was surprised to find the papers I had had ______ was missing.A.to collect B.collected C.it collected D.to be collected请详细说出理由.thanks! upon arriving home ,the girl discovered that she had left her bag at her friend's.这里面的upon是什么意思? ...upon arriving at her class each day中的upon I will be arriving 英语句子判断正误When are you arriving at Beijing?I am arriving at five .Where are you staying?I staying in my uncle's home. 英语翻译(1).I saw what a hard time my parents had upon arriving in this country.(2).I saw the hard time my parents had upon arriving in this country.(3).I saw what a hard time my parents had arriving in this country.为什么? _,we went boating and enjoyed the beautiful scenery of the sea under the rising sun.A.Upon arriving B.Upon to arrive C.With arriving D.Arriving ________at the airport ,he telephoned his wife and told her what he would do when he got home .A.Once arrivedB.As soon as he reachedC.When he gotD.Upon arriving可是答案为什么选D呢 ■一道初中英语题(说理由）upon arriving home the girl discovered that she ______ her bag at her friend'sA.left B.had left C.forgot D.had forgot as soon as,upon,on的区别举例说明后面应该加什么!例题：_________ arriving home,she threw herself into the sofa,exhausted.A.On B.In C.As soon as D.The moment _____at the airport,he telephoned his wife and bold her what he would do when he got home.A.Once arrived B.As soon as he reached C.When he got D.Upon arriving arriving arriving什么意思I kouw you are arriving next Sunday. Dick,your father has returned home and hopes you will be back this evening.That's great.I thought he____tomorrow.A.was arriving B.will arrive C.is arriving D.arrives Li Ming is arriving home from BeiJing.如何翻译?