Put some cartons on the table, tap the table with your hand and see death. If Chen doesn't teach, it means that it can't be sold. This shows that.

When the horn doesn't ring, the foam on the paper basin is static, but when the horn rings, the foam on the paper basin is alive and kicking. This phenomenon shows that everything that makes a sound vibrates, and when the vibration stops, the sound disappears.

The sound of a pencil hitting the desktop can be heard when the ear is attached to the desktop, which shows that the sound can spread in the solid;

Being able to judge a classmate's voice is judged according to the different timbre of the voice;

There is no air on the moon, vacuum can't spread sound, and astronauts can't talk directly on the moon.

So the answer is: vibration; Solid; Timbre; Vacuum.