(1) An action that continues in the present.
(2) A way of expressing a future action.
(1) The receptionist says that it isn't possible to talk to the chief clerk because she is discussing marketing with her colleagues.
(2) To improve staff relationships in the research and development group all the staff are taking part in a team bonding project next month.
Both sentences are positive. In order to make them negative we have to change them as: (1) she isn't (is not) discussing (2) the staff aren't (are not) taking part.
Both sentences are statements. In order to make them interrogative, we have to change them as: (1) is she discussing? (2) are the staff taking part?
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