arbeiten: stem = arbeit + infinitive ending = en
Er arbeitet.
Wo arbeitest du?

finden: stem = find + infinitive ending = en
Sie findet Geld?
Findest du oft Geld?

regnen: stem = regn + infinitive ending = en
Es regnet.

Study the three photos above and read their captions. When you want to form the present tense of a verb whose stem ends in -d or -t (and in many cases also in -n), it will be very difficult to pronounce the verb-form once you have added a -t or an -st. Therefore, a letter is inserted before the ending to facilitate pronunciation. Which letter is inserted?

Write the letter into the gap provided and fill in the gaps under the two photos on the right-hand side. Then press [Check] to see if you got it right. Use the [Hint] button to get a free letter if you need help.

And don't worry. You will probably insert the extra letter automatically once you try to pronounce the verb-form.