1. 区域   cone   semicircle   angle   area   Hint Half-n-half Clue   2. 圆周   perimeter   rectangle   curve   circumference   Half-n-half Clue   3. 三角   triangle   area   angle   circle   Half-n-half Clue   4. 容量   cone   volume   sphere   line   Half-n-half Clue   5. 立方体   circumference   perimeter   square   cube   Half-n-half Clue   6. 周长   square   cylinder   circle   perimeter   Half-n-half Clue   7. 线   cone   line   area   volume   Half-n-half Clue