In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

Question: What are drilled to monitor groundwater pollution? Answer: test wells
Test wells are drilled to monitor groundwater pollution.

Question: What type of energy travels through matter in wave form? Answer: sound
Sound energy travels through matter in wave form.

Question: What is the outer core made of? Answer: liquid metal

The outer core is made of liquid metal.