一...就...如：IfoundmyselfinanentirelynewworldthemomentIarrivedinBeijing.我一到北京就感到耳目一新.

　　它的用法就和when差不多？

　　不是完全正确，考查“一……就……”表达法表示“一……就……”的连词有：①assoonas;②themoment=theminute=theinstant;③immediately=directly;④hardly…when…=nosooner…than…等。例如：1.Assoonas/Themoment/Theminute/Immediatelyhesawthebear,heclimbedthetree.他一看见熊就立刻爬上了树。2.Ihadhardlysatdownwhenhesteppedin.=Ihadnosoonersatdownthanhesteppedin.=HardlyhadIsatdownwhenhesteppedin.=NosoonerhadIsatdownthanhesteppedin.我刚坐下，他就进来了。