英语时态：The official stamp showed that my documents are valid.为什么show用过去式,后面却用are?为什么不是这样：The official stamp shows that my documents are valid.The official stamp showed that my documents were valid.
问题描述：
英语时态：The official stamp showed that my documents are valid.为什么show用过去式,后面却用are?
为什么不是这样：
The official stamp shows that my documents are valid.
The official stamp showed that my documents were valid.
答
因为前面已经过去时，后面就是be动词就原型了。比如I didn't play computer和I played computer last week
答
因为the official stamp已经被按了上去，是已经过去的事了， 而documents现在还是有效，这个文件还是在现在式，
按原句翻译再加上意思就是， 已经盖上的公章表示我的文件从现在开始是有效的了
答
在你看到文件之前,official stamp (公章或邮戳）肯定是已经盖在了文件上,所以要用过去式showed.另外,文件有效指的是一种恒常的状态,状态是可以一直持续的,况且,是阅读后看后才知道文件是否有效.一般来说,主句用了过...