1,
established (past simp - establish),
has been (pers perf - be)
2. began (past simp - begin) was (past simp - be), know (pres simp - know)
3. developed (past simp - develop)
4. may (pres simp - may), exist (infinitive - exist), is (pres simp - be)
5. have (pres simp - have)
6. dissolves (pres simp - dissolve), is (pres simp - be)
7. had found (past perf - find), could (past simp - can), investigate (infinitive - investigate)
8. have found (pres perf - find), are (pres simp - be), are (pres simp - be)
9. has (pres simp - have)
10. believe (pres simp - believe), has changed (pres perf - change), was (past simp - be)