Rewrite the sentences using the present perfect active.
11. these chemical elements have been used in their experiment.
12. the observations have been recorded by the scientist.
13. the problem has already been settled.
14. the probability of passing on a hereditary disease has been determined.
15. the discussion hasn’t been finished yet.
1)They used these chemical elements in their experiment
2)Scientists have recorded observations
3) I settled the problem.
4)Scientists have determined the probability of transmission of hereditary disease.
5)We haven't finished the discussion yet