The Present Continuous is the tense used to express an action at the time of being performed.
It is a complex tense (two verbs). A sentence with the verb in present continuous is always composed by:
Subject + present of the verb “be” + verb-ing + complements
— I am writing on the blackboard now.
THERE ISN'T PRESENT CONTINUOUS WITHOUT VERB "BE"
To turn a sentence with the present continuous into interrogative or negative is like doing it with any sentence with the verb “be”; that is subject-verb inversion for interrogatives and direct negatives.
— My father is waiting for me at this moment.
→ Is my father waiting for me at this moment?
→ My father isn’t waiting for me at this moment.
Differences between Present Simple and Present Continuous
Present Simple
→ Simple tense (one verb)
→ Auxiliary verb “do” for interrogatives and negatives (except with “be”, “have got” and “can”).
→ Used for habitual actions, they happened in the past, they happen in the present and in the future.
Present Continuous
→ Complex tense (two verbs) be + -ing.
→ Subject-verb inversion for interrogatives and direct negatives.
→ Used for actions at the moment of talking.