say good-bye to one's friend

In a twinkling, the clock on the wall struck nine. We could not but say Good-bye to one another.

转瞬间，墙上的钟敲九点了。我们不得不互道再见。

And although these biofuels will probably first be supplied preblended with traditional gasoline or diesel, one day we may use them alone and say good-bye to petroleum-based gasoline forever.

当然，刚开始的时候，这类生物燃料还是只能与传统的汽油或柴油混合使用，但迟早都有能够单独使用的一天。 到了那一天，我们就可以永远告别利用石油来提炼汽油的时代。

Recently one of my friends is extremely anxious and nervous to say good-bye.

近来我有一个朋友对说再见很焦虑、很紧张。