Delve into the checkered past of Professor Pfrehm as you learn about ... the past-the simple past, that is. This tense is different in form from the present perfect you learned in Lessons 13-15, but its meaning is the same, though it is mostly used in formal writing. Cover the simple past forms of the verbs sein, haben, and geben, and the modal verbs mussen, konnen, mogen, durfen, wollen, and sollen.