1. hole
2. opening
3. orifice (of the human body)
4. (fig.) key (to the solution of a problem)

1. gate
2. door
3. gateway
4. doorway
5. opening
6. valve
7. switch
8. way to do something
9. knack
10. family
11. house
12. (religious) sect
13. school (of thought)
14. class
15. category
16. phylum or division (taxonomy)
17. classifier for large guns
18. classifier for lessons, subjects, branches of technology
19. (suffix) -gate (i.e. scandal; derived from Watergate)

classifiers: 扇, 個