1. crucial point
2. crux
3. key
4. crucial
5. pivotal

classifier: 個

1. to touch briefly; to tap
2. to mark with a dot; to check off (on a list)
3. to order (food etc); to select
4. to mention; to bring up (a topic or person)
5. to hint at; to imply
6. to administer (eye medicine etc) in drops
7. to light (a fire, a lamp etc); to ignite
8. to nod (one's head) in agreement; to beckon by moving (one's hand) up and down
9. point; dot; spot; speck
10. dot stroke in Chinese characters
11. (math.) decimal point
12. point in time or space
13. (after a number) o'clock
14. a small amount; a bit; (after a verb or adjective) a bit more
15. classifier for small amounts