急.高一英语句子转换题!
Uponhisarrivalattheoffice,herealizedhehadlefthismobilephoneathome.
Immediately_________theoffice,herealizedhehadlefthismobilephoneathome.
两空到底怎么填啊?为什么呢,这里Immediately是作连词的,一.就.,但后面加什么呢,arrivingarrived为什么呢,immediately作连词的用法?