试管里装着各种颜色的液体。

The test ___tubes contain liquids of various colors.

工人们在安装新的水管来输送热水。

Workers are installing new ___tubes to carry hot water.

我们乘地铁去参观大本钟。

We used the ___tube to visit Big Ben.

我需要更换自行车的内胎，因为它漏气了。

I need to replace my bike's ___tubes because they're leaking air.