1. to / in / at / -
2. is living / lived / live / have lived
3. to / for / at / -
4. is narrowing / are narrowing / narrows / narrow
5. no one / anybody / anyone / none
6. weather / or / whether / of
7. spew / spewed / spewing / spews / oozing
8. must have precipitated / could have precipitated / should have precipitated / might have precipitated
9. prompt / prompted / have prompted / has prompted
10. at last / at least / at once / at a glance
11. more recent / more recently / recently / recent
12. must have been seen / encountered / encountering / have encountered
13. no / any / anyone / nobody
14. little / few / a few / a little
15. descendants / child / child's / offspring
16. it's / its / their / they're