看到一句It is 3 years since he joined the army.和一句It has been three hours since he left his office. is和has been可以互换?

看到一句It is 3 years since he joined the army.和一句It has been three hours since he left his office. is和has been可以互换? It is 3 years since I smoked.意思?语法好的看看我在知道上看到的,关于since 用法别人提供的一个回答.eg.It is 5 years since I have lived here.(live为延续性v.故直译为自从我住在这儿已经5年了.) It is 5 years si he is poor .he si very happy.合并一句 People say that it is 100 years old.同义句------- --------that it is 100 years old. 这句 it is cleaner than was 100 years my father is 40 years old.my mother is 40 years old,too.（合并为一句）（ ）my father （ ）my mother（ ）40years old.It's noisy outside now.What h______?谢谢 It is ten years since his father died..同意句his grandpa ------- -------- ------- -------ten years ago Lucy is ten years old.Tom is ten years old,too.合并为一句 Tom is twelve years old,Mike is thireen years old.合并为一句 tom is ten years old.kate is eight years old.（合并为一句） Tom is five years old.Peter is six years old.(用比较级合成一句) Lucy is 10 years old.Tom is 13 years old.合为一句 Tom is 12years old.Jack is 13 years old.(求合并为一句) katy is 13 years old .sandy is 15 years old .合并为一句 将he is 12 years old.和she is 11 years old.合成一句 Tom is 5 years old.Sam is 8 years old.(合并为一句) Ann is twenty years old.Lucy is eight years old.连成一句. Bob is 18 years old.Mike is 19 years old.合并为一句