B1 students must choose between four tenses based on the nature of the action:
Use for habits, facts, and permanent states. (e.g., I work in New York.)
Use for actions happening now or temporary situations. (e.g., I am working from home today.)
Use for past actions with a current result or experience. (e.g., I have finished the report.)
Use for ongoing actions emphasizing duration or recent activities. (e.g., I have been working for hours.)