Unless you are explicitly told otherwise, only pour down lab sinks.

Unless you are explicitly told otherwise, only pour      down the lab sinks.

It has to be three elements long, using the initial for the element. Looking at the periodic table of elements, we can find the following elements.

This leads us to the

W- Tungsten

AT- Astatine

ER- Erbium

W-AT-ER

Water!

I hope this helps! :)

let that person have a turn to speak : )

gas

explanation:

smoke is the matter of a gas