Form abstract nouns using appropriate suffixes.
1. able- ........................
2. difficult .................
3. explore...................
4. warm...................
5. hero...................
6. false................
7. agent...............
8. brave....
9. young......
10. high....
11. vain........
12. consistent.....
13. grow..........
14. invite....
15. judge........
16. neighbour................
17. member............
18. king..............