To sleep
•Present simple
Affirmative: I sleep.
Negative: I don't sleep.
infinitiv: to sleep
• Present Continous
Affirmative: I was sleeping.
Negative: I wasn't sleeping.
•Present perfect simple
Affirmative: I have slept.
Negative: I haven't slept.
• Present perfect continous
Affirmative: I have been sleeping.
Negative: I haven't been sleeping.