过了好一会儿我才意识到他是在开玩笑。

It took a few moments ___before I realized that he was joking.

我们等了几个小时公交车才终于到达。

We waited for hours ___before the bus finally arrived.

她练习了几个星期才能完美地演奏那首歌。

She practiced for weeks ___before she could play the song perfectly.