Present Simple Continuous:
i'm studying very hard.
you're going to school.
they're trying to find their homework.
he's purchasing some new shoes.
she's running at the streets.
Joe is practicing some sports.
Past Simple Continuous:
I was checking my E-mail last night.
You were working too hard lately.
She was crying out all day long.
Present Perfect Continuous:
You've been seeing several movies since you bought the new TV.
he's been doing his homework.
Gerund as Subject.
Exercising is the best way to lose weight.
Cooking is her hobby.
Studying is his passion.
there are more ways to use gerunds but these are which i can remember by now... hope it can help you