They had hardly arrived when it began to snow.和They were abo

They had hardly arrived when it began to snow是对过去时的虚拟= Hardly had they arrived when it began to snow
They were about to leave when it began to snow.是真实语气=They were leaving when it began to snow.他们正要打算出发时天开始下起雨来.be about to do 正要干.（真实语气）
再问： They had hardly arrived when it began to snow是不是翻译成‘他们一到就下雪了’但是没发现虚拟语气啊
再答： 他们一到达天就下雨了。（是一种虚拟语气，到达和下雨两个动作无法衡量是同时发生的，第一个雨点何时下来的？所以只是说 他们到达的时候没怎么被雨淋着 而已） hardlly ...when ...一。。。就。。。（=真实语气的as soon as...)