Definition: If a drink is flat, it does not contain enough bubbles of gas. Level: C2
如果你不把苏打水瓶的盖子盖回去，它就会跑气变淡。
If you don't put the top back on the soda bottle, it will go ___flat.
这啤酒开得太久，尝起来完全没气了。
The beer had been open too long and tasted completely ___flat.
庆祝会上，走了气的香槟令人失望。
The ___flat champagne was a disappointment at the celebration.
