Present Continuous and Simple Present (2)

When think means "believe," do not use the continuous:
     - What do you think(= believe) will happen? (not What are you thinking)
but - You look serious. What are you thinking about? (= What is going on in your mind?)
     - I'm thinking of quitting my job. (= I am considering)


When have means "possess," etc., do not use the continuous:
     - We're enjoying our trip. We have a nice room in the hotel. (not We're having)
but - We're enjoying our trip. We're having a great time.


We normally use the simple present(not continuous) with these verbs:
See   hear   smell   taste
- Do you see that man over there? (not Are you seeing)
- This room smells. Let's open a window.
Note that you can say I'm seeing when the meaning is "having a meeting with"
(especially in the future)
- I'm seeing the manager tomorrow morning.


He is selfish and He is being selfish
He's being = He's behaving / He's acting. Compare:
     - I can't understand why he's being so selfish. He isn't usually like that.
        (being selfish = behaving selfishly at the moment)
but - He never thinks about other people. He is very selfish. (not He is being)
        (= he is selfish generally, not only at the moment)



<excerpts from Grammar in Use Intermediate>