input question: Determine the topic of the question. Question: "who rules communism government?" Topic:???
output answer: Communist state

Determine the topic of the question. Question: "how does a solid state drive work?" Topic:
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Answer: Solid-state drive

Q: Determine the topic of the question. Question: "what is puerto rico currency?" Topic:
A: Currencies of Puerto Rico

Question: Determine the topic of the question. Question: "what is file based system?" Topic:
Answer: File system

[Q]: Determine the topic of the question. Question: "what is the format of the canadian citizenship test?" Topic:
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[A]: Canadian Citizenship Test

Problem: Given the question: Determine the topic of the question. Question: "how are aircraft radial engines built?" Topic:
++++++++++++++++++++++++++++++++
The answer is:
Radial engine