1. 半圆   line   curve   side   semicircle   Hint Half-n-half Clue   2. 正方形   triangle   square   radius   circumference   Half-n-half Clue   3. 长方形   volume   circumference   rectangle   triangle   Half-n-half Clue   4. 曲线   radius   cube   angle   curve   Half-n-half Clue   5. 圆周   circumference   sphere   semicircle   circle   Half-n-half Clue   6. 边   rectangle   sphere   side   curve   Half-n-half Clue   7. 锥体   rectangle   cone   point   circumference   Half-n-half Clue