1. 圆周   rectangle   diameter   circumference   semicircle   Hint Half-n-half Clue   2. 球形   square   radius   cylinder   sphere   Half-n-half Clue   3. 正方形   triangle   square   radius   perimeter   Half-n-half Clue   4. 直径   diameter   radius   cylinder   curve   Half-n-half Clue   5. 区域   circumference   angle   area   cylinder   Half-n-half Clue   6. 半径   area   radius   line   circumference   Half-n-half Clue   7. 锥体   cone   circumference   side   semicircle   Half-n-half Clue