1. 凹面   parallel lines   quadrilateral   edge   concave   Hint Half-n-half Clue   2. 四辺形   vertex   quadrilateral   segment   polygon   Half-n-half Clue   3. 凸面   convex   quadrangle   edge   ellipse   Half-n-half Clue   4. 菱形, 斜方形　   rhombus   oval   concave   ellipse   Half-n-half Clue   5. 半球体   oval   hemisphere   perpendicular lines   straight line   Half-n-half Clue   6. 区切り、部分   concave   quadrangle   ellipse   segment   Half-n-half Clue   7. 垂線　   vertex   oval   polygon   perpendicular lines   Half-n-half Clue