This is an exercise using a modal verb and a verb in one sentence. When you have a modal verb (such as "wollen"), you conjugate it and use it first and push the actual verb (in its infinitive form) to the end,e.g. #1:
1.) du: mich gegen sieben anrufen / können
Du kannst mich gegen sieben anrufen.
There is also a question that does not have an actual verb, but only a modal verb. So only the "nicht" gets pushed to the end:
5.) warum / du: diesen Kaffee / nicht mögen
Warum magst du diesen Kaffee nicht?