I’ve written her 20 letters since I was here.这句话啥意思?

I’ve written her 20 letters since I was here.这句话啥意思? I've been here since 1976.这句话中been后面为什么不加to I've been here since 1976. 这句话中been后面为什么不加to I've written words that I never knew were in the world这句话的句子 I have not seen her since 1997保持原句意思 I saw her was in1977 I have written six letters to Joe since then.(改为被动句) Six let 英语译文I haven't written many letters to you before,as we've al 求翻I've been here since 1990 英语翻译I have written three letters,he was never answered.I wro I 've know him since he came here.(对划线部分提问since he came here That's changed since I came here.按照整句话的意思,这句话不是应该用过去完成时吗? I've never been here 什么意思