question: How big is the largest copper crystal that has been found ?
answer: 4.4 × 3.2 × 3.2 cm
turker_answer: The largest copper crystal that has been found is 4.4 × 3.2 × 3.2 cm .
rule-based: The largest copper crystal that has been found is 4.4 × 3.2 × 3.2 cm .