It would be a momentous event.

这将是意义重大的大事件。

"This is going to be a pretty momentous event," he said.

他说：“这将是一次颇具历史意义的会议。”

It is a momentous event, something we will tell our children's children about.

像这样重大的事件，日后一定会在我们的儿孙辈间传述。

In my view, this world conference must be the third momentous event of the year.

在我看来，本次世界大会必须成为今年第三项重大事件。

Two weeks ago a momentous event occurred: the beginning of the world's first evacuation of an entire people as a result of manmade global warming.

两星期之前发生了一件重大事件：人为的全球变暖造成恶果，世界上首批居民整体迁移开始了。