Fill in the correct verbform (Modalverb)!
German Exercise Manual:
If you think you know the correct answer of any question fill
it in. After clicking on the button "Submit your answers"
correct answers are marked with green colour and an icon. You
do not have to fill in all the answers before you press the
button: Unanswered sentences and incorrect solutions are left
open so that you can try again. Sometimes the correct answer
will be a blank text field. In this case, fill in "-"‘.
Note: The text fields are sensitive to capitalized letters.
In case you get stuck click the help icon and get the correct answer letter by letter.