"时间过了许久"可以用英文表达为 "time has passed by" 或者 "time has gone by." 这个表达方式源自于英语中 "pass" 和 "go" 的意思，它们都可以表示时间流逝。例如：

Time has passed by quickly since we last saw each other. 我们上次见面以来时间过得真快。
It's been a long time since we last spoke. 我们上次说话以来已经很久了。

"pass" 和 "go" 还可以用来表示其他的东西流逝或经过，例如：

The train passed by my house at 5:00 this morning. 今天早上5点时，火车经过了我家。
The storm went by quickly, and now the sun is shining. 暴风雨过去得很快，现在太阳正在照耀。

"pass" 和 "go" 还可以用来表示某些事情完成，例如：

The exam went by quickly. 考试过得很快。
The hours passed by slowly as I waited for news. 当我等待消息时，时间过得很慢。

希望这些例句能帮助您理解 "时间过了许久" 的英文表达。