Question

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

Answer 1

The answer may be Safe liquids?

Answer 2

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 answer:

W- Tungsten

AT- Astatine

ER- Erbium

W-AT-ER

Water!

I hope this helps! :)