as is often the case 和 as often happens为什么第一个中要加is而第二个不用呢?

as is often the case? She is absent, as is often the case.译文 As is often the case和A case in point is As the case is often和As it often the case As is it 和As it is 有什么区别? 【急】as is often the case中的as为什么不能换做whichas is often the case中的as为什么不能换做whicheg.As is often the case,he didn't study hard and failed to pass the exam. Li Ming is late, as is often the case中as为什么不能用which替代 as is often the case的语意及as的全方位综合用法 as is often the case 和 as often happens为什么第一个中要加is而第二个不用呢? He is absent,( )is often the case A.which B.as一定告诉我为什么, Li Ming is late,as is often the case.为什么不能用which there is no simple answer (as)is often the case inscience.为什么不能用where He is absent _ is often the case.A what B which C who D as he is absent,( )is often the case A.what B which Cwho D as As is often the case,we have worked out the plan.这句话怎么翻译呢? as is often the case,we have worked out the production plan中文如何翻译 As is often the case,we have worked out the production plan. David,___is often the case,is late for class.为啥添as 时态填空：He is late,as?（be）often the case.