我只是在很久以前听说过这件事。 I only heard of the story in the far past.
那是很久以前的事了。 That was a great while ago.
在很久很久以前，牧童都是游牧者，赶着他们的牧群到处寻找青草和水源。 A long, long time ago, cowboys were wanderers, driving their herd from place to place, looking for fresh grass and water.
很抱歉，我想不起来了--那是很久以前的事了。 I'm afraid I can't remember it was such a long time ago.
很久以前，地球上生活着巨大的动物。 Long ago enormous animals lived on the earth.
