Present Simple
1)They work at the office.+
They don't work at the office.-
Do they work at the office?
2)My uncle often meets his wife at her office.+
My uncle doesn't often meet his wife at her office.-
Does my uncle often meet his wife at her office?
3)They usually buy interesting books in London.+
They don't usually buy interesting books in London.-
Do they usualy buy interesting books in London?
Present Coontinuous
1)He is reading a book at home now.+
He isn't reading a book at home now.-
Is he reading a book at home now?
2)Ann is sitting at the table.+
Ann isn't sitting at the table.-
Is Ann sitting at the table?
3)He is doing work for this lawer.+
He isn't doing work for this lawer.-
Is he doing work for this lawer?
Present perfect
1)He has already finished your homework.+
He hasn't finished your homework yet.-
Has he finished your homework yet?
2)They have already chacked a file.+
They haven' already checked a file yet._
Have they checked a file yet?
3)I've finished my work already.+
I Haven't finished my work yet.-
Have you finished yor work yet?