TASK DEFINITION: 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.
PROBLEM: Question: Organisms categorized by what species descriptor demonstrate a version of allopatric speciation and have limited regions of overlap with one another, but where they overlap they interbreed successfully? Answer: ring species

SOLUTION: Organisms categorized by ring species species descriptor demonstrate a version of allopatric speciation and have limited regions of overlap with one another, but where they overlap they interbreed successfully.

PROBLEM: Question: What forms when nitrogen and oxygen combine at high temperatures? Answer: nitrogen oxide

SOLUTION: Nitrogen oxide form(s) when nitrogen and oxygen combine at high temperatures.

PROBLEM: Question: What device is used to study charge? Answer: electroscope

SOLUTION:
A(n) electroscope is used to study charge.