Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Human facial expressions can communicate emotions.
What can human facial expressions communicate?

If a substance has a ph value greater than 7,that indicates that it is base.
If a substance has a ph value greater than 7, what does it indicate?

A(n) arachnid has additional appendages called the chelicerae and the pedipalps.

What class of invertebrate animals has additional appendages called the chelicerae and the pedipalps?