It was a wonderful planet!为什么是was(过去式）呢?不应该是is吗?

It was a wonderful planet!为什么是was(过去式）呢?不应该是is吗? It is called a clavichord.中的called是过去式吗?如果是,那为什么还用is而不是was呢? 求It was a wonderful planet.变一般疑问句谢谢指教 it is ...since it was...before 一定是过去式吗? 为什么用过去式呢.was. a:_______in america?b:it was wonderful. 英语翻译It was a man who was standing outside who后是宾语从句吗？为什么It不翻 wonderful和How wonderful it was一样吗? it was important not to go near a snake为什么是过去式? 能不能用How wonderful music it was! 英语翻译The computer is a wonderful machine.It was invented not ____ wonderful concert it was!