I met her once, briefly.我曾经和她有过短短的一面之缘。

I've been to France once before.我以前曾经去过一次法国。

once a week每周一次

once a month每月一次

once every fortnight每两周一次

once every three months每三个月一次

Texas was once ruled by Mexico.得克萨斯州曾经归墨西哥管辖。

I knew him once.我以前认识他。

My memory isn't as good as it once was.我的记忆力不如以前好了。

a cousin once removed隔一代的堂亲(或表亲)

if you once forget it你一旦忘记它的话

Once again British justice has appeared to falter.英国司法制度似乎再次显现出颓势。

She wanted to see him once more before she died.她想在临死之前再见上他一面。

They had to be defeated once and for all.必须彻底击败他们。

Every once in a while we go to the cinema.我们偶尔会去看电影。

She had been to London once or twice before.她以前去过伦敦一两次。

Once upon a time there were three princes.很久很久以前, 有三位王子。

Once upon a time, I wanted to change the world.想当年, 我曾想改变这个世界。

Once inside her flat, she opened the letter.一回到自己的公寓, 她就拆开了那封信。

Once you have kids, your priorities change.一旦有了孩子, 你的生活重心就会发生变化。

Can I borrow your car?—All right then, just this once.我能借一下你的车吗？——那好吧, 仅此一次。

All at once there was someone knocking on the door.忽然有人敲门。

I knew at once that something was wrong.我立刻意识到情况不妙。

They all arrived at once.他们都是同时到达的。

Everybody is talking at once.所有人都同时在说话。

It was at once a question and a command.这既是询问, 也是命令。

She was able, for once, to relax.只有这一次, 她能够放松一下。