1: We use the present continuous for actions that start and finish within a timeframe. We often say the action is happenign now.
- What are you doing?
- I'm calling my friend. (The action will stop soon)
- What are you watching on TV?
- I'm watching a documentary about the Olympics.
2: We use the present simple tense for an action that is repeating or ongoing. We use the present continuous if the action will end at some time.
- I live in New York.
- I'm living in New York at the moment. (I will move at some point)
- I work a lot.
- I'm working a lot these days. (I will work less soon.)
3: In fast spoken English, the be verbs are contracted and the /g/ in the /-ing/ is ommited.
- I am having a good time.
- I'm havin' a good time.
- She is making a big mistake.
- She's makin' a big mistake.
- He is not coming to the party.
- He isn't comin' to the party.
4: We often use the present continuous for plans in the future, especially if the action is known or anticipated by other people.
- Are you coming to the party tomorrow night?
- Yes, I'm going, but I'm working tomorrow, so I might be late.
- Is anyone coming with you?
- Yes, I'm bringing my friend.