as位于句首各是什么用法?1.as often happens2.as is often the case3.as it

As the case is often和As it often the case As is it 和As it is it is necessary ------- you ------- English as often as you 句中的as什么用法 充当什么角色 As is often the case with. as is often the case的语意及as的全方位综合用法 The best way to learn English is（）it as often as possible.A as far as,as long as,as well as,as often as more often than 和as often as as often as you can is good for you She is absent, as is often the case.译文 as is often the case,we have worked out the The young trees should _____ well as often as possible use the word as often as you can的意思