It is 5 years since that ... I keep it in my mind

It is five years since he smoked 翻译It is 5 years since that ...I keep it in my It is 5 years since that ... I keep it in my mind It is 5 years since I have lived here.It is 5 years since I lived here.这两句话分别译为? it is ...since ..为什么不用完成时it is 100 years since Qinghua university was found. It is about 5 years () he came to our school填since or for填哪个? It is 5 years since this problem _____(appear) in this city. It is years since we meet last time.（纠错） It is three years since she was in the It is ten years since he ____(join) the army it is 3 years since Tom has been abroad It is forty years since he home 改为间单句 it is years since i saw him（追加）it is years since i saw him为什么不说it is years since i has seen him而it was years since i had seen him 却可以 it is two years since I came here还是it has been two years since I came here 求It is three years since he worked in his office.解释下since it's years since i He smoked since 2 years ago .怎么翻译?等不等于It is 2 years since he smoked. It is ten years since his father died..同意句his grandpa ------- -------- ------- -------ten years ago