这杯柠檬水没气了。

This lemonade is ___flat.

这瓶香槟开了好几个小时，气泡已经完全跑光了。

The champagne had been open for hours and was completely ___flat.

我把苏打水放在外面过夜，现在它已经变平淡了。

I left the sparkling water out overnight, and now it's ___flat.