1. 症结：6. lever 杠杆;用杠杆撬动 | 7. crux 症结 | 8. ideologue 空想家,思想家
2. 关键：crura cerebelli 小脑脚 | crux 关键 | cryaesthesia 冷觉过敏
3. 南十字星座：crux head 十字头 | Crux 南十字星座 | Crux 南十字座
1. (难题或辩论的)关键，最难点，症结
The crux of a problem or argument is the most important or difficult part of it which affects everything else.
e.g. He said the crux of the matter was economic policy.
他说问题的症结在于经济政策。