TASK DEFINITION: In this task, you are given a sentence and a question, you would be asked to create the answer which is contained in the sentence provided.
PROBLEM: Sentence: Primary pollutants enter the air directly. Question: What type of pollutants enter the air directly?

SOLUTION: primary

PROBLEM: Sentence: Combustion reactions involve the reaction of a hydrocarbon with oxygen gas to produce water and carbon dioxide. Question: What involves the reaction of a hydrocarbon with oxygen gas to produce water and carbon dioxide?

SOLUTION: combustion reactions

PROBLEM: Sentence: Some compounds form rigid frameworks called crystals. Question: Some compounds form rigid frameworks called what?

SOLUTION:
crystals