Bhai.Are these sentences grammatically correct? Might they have a different meaning?
a 1) She might have gone to see her dentist. She is not here or she wasn't here, I am not sure where she is, perhaps she is at or on her way to see the dentist.
2) She might have been going to see her dentist. When you saw her in X street, she was, perhaps, on her way to see the dentist.
3) She might be going to see her dentist. She might have an appointment with her dentist.
b 1) They could be arriving at any moment.
2) They could arrive at any moment. These mean the same.
c 1) I'll have left before the clock strikes twelve.
2) I'll have been leaving before the clock strikes twelve. This is incorrect.
d 1) The new occupants will be getting in at 12.
2) The new occupants get in at 12. They will come home at 12. (I and 2)
3) The new occupants will be moving in at 12.
4) The new occupants move in at 12. They are moving in to their new home at twelve. (1 and 2)
e 1) I think we better leave as soon as they bring us the bill.
2) I think we better leave as soon as they have brought us the bill. Both incorrect.
f 1) Our builder told me he would do the best to get the materials soon. He hasn't done his best yet, but he will.
2) Our builder told me he was doing the best to get the materials soon. He is doing his best at the moment.
3) Our builder told me he had done the best to get the materials soon. He did his best in the past to arrange the delivery soon.