"two years ago "不是表过去时吗?为什么可以与现在完成时连用?(since two years ago)而

"two years ago "不是表过去时吗?为什么可以与现在完成时连用?(since two years ago)而 since two years ago 中但是ago不是标志过去式吗?不矛盾吗 since two years ago与since two years的区别,分别用在什么时态? SINCE TWO YEARS AGO的同义句 since可以和ago连用吗,不是说用现在完成时,就不能出现ago吗 the swimming club opened two years ago（用since two years ago two years ago 前面用一般过去时还是现在完成时 We-------students two years ago. Mr green has ()us English since two years ago They ___(live) there since two years ago How long ___ your mother ___?Since two years ago. Since they(visited/have visited)hangzhou two years ago,they(