Ребят, помогите, пожалуйста! Спасибо заранее!!

Поставьте глагол в Future Perfect.
1) The scientists think that they (to prove) their conclusion by the end of their experiments.
2) I think that I (to accomplish) my investigation by the beginning of the next year.
3) The researcher (to isolate) the necessary substance before he begins a new experiment.
4) Do you think we (to complete) our observations by the next month?

1) The scientists think that they (will have proved) their conclusion by the end of their experiments. 2) I think that I (shall have accomplished) my investigation by the beginning of the next year. 3) The researcher (will have isolated) the necessary substance before he begins a new experiment. 4) Do you think we (shall have completed) our observations by the next month?