Student or Learner
Which tense is correct? The present simple or continuous?:
-You have to pay attention when you use/are using "she, he or it". It's necessary to add an "s" at the end of the verb present form".
The difference is that the present simple has the underlying idea of each and every time that you use, whereas the continuous has the idea of whenever you happen to find yourself using. Those are rough paraphrases!