Since that和 since then是一样的吗?为什么?

since then 和since that有什么区别? Since that和 since then是一样的吗?为什么? since that 和 now that区别~ since since then可以说成 since that time from ever since和since then和after that time和from then on的区别? in that是否等于since和now that 请问since与since that在意思和用法上有什么区别? have since been 和 have been since now that和since作既然讲,有什么区别? since和for用法 比较since和for During studies,it is found that more than 60 percent of famous paintings since the 14th century During studies,it is found that more than 60 percent of famous paintings since the 14th century We have since confirmed that……中“since”的意思和用法是什么?We have since confirmed that……这个句型中,“since”的意思和用法是什么? 关于since和beforeIt was two years___he came back from abroad.A.since B.that C.when D.before He told us that he had worked here since 10years before.这个句子对么?在此处since和before连用怎么讲?since 10years before完全等于since 10 years ago么？ since的意义和用法