Welcome to the forum.
I'ts very difficult to concept-check habit and routine when you can't contrast them with anything else. If you are really expected to work with affirmative forms only, is it possible that you may be being asked to work with form rather than function? By form I mean the third person singular ending: when is -s added, and when -es? What are the 'rules' for pronouncing the -(e)s ending in three different ways? If you are working with course books, have a look at the Teacher's Book, and see what suggestions are made there.
Student or Learner