"Time has come to do something." 或者 "It's time to do something." 均可表达做某事的时间到了。其中，"Time has come to do something." 更为正式和庄重，适用于正式场合或者正式文体；而"It's time to do something." 则更为通俗易懂，适用于日常口语和非正式场合。此外，还可以使用其他表达方式，例如 "It's about time to do something." 或者 "The moment has arrived to do something." 等等。