1. si [bian;bian] xing   pyramid   perpendicular lines   quadrangle   rhombus   Hint Half-n-half Clue   2. chui zhi xian   concave   perpendicular lines   parallel lines   vertex   Half-n-half Clue   3. wu [bian;bian] xing   ellipse   pentagon   parallelogram   ray   Half-n-half Clue   4. [ao;wa] mian   hexagon   ellipse   concave   plane   Half-n-half Clue   5. jin zi [da;ta]   pyramid   plane   oval   quadrangle   Half-n-half Clue   6. luan xing   hemisphere   oval   ray   segment   Half-n-half Clue   7. si fang xing   convex   oval   quadrilateral   hemisphere   Half-n-half Clue