Exercise 2: Present Simple, Past Simple or Present Perfect

Which tense is usually best for each of the following situations?

Change the drop down at the end of each sentence to present simple, past simple or present perfect, to see how it reads in each format.

E.g. if you think a theory is best expressed in the present perfect, select 'present perfect' in the drop down box. Then click 'submit' to see if your answers are correct.