当他进来时,我正在做作业 用英语怎么说

as soon as 引导时间状语从句,表示“一……就……”.如果主句用将来时或情态动词或祈使句,从句必须用一般现在时代替将来时.如：
I’ll tell him the news as soon as he comes.
他一来我就告诉他那消息.
She may come as soon as she finishes the work.
事情一做完她就可以来.