Grammar in Use

Present Simple-Present Continuous-Present Perfect Simple-Present Perfect Continuous

Present Simple (PS) is used for describing permanent situations (daily routine)

Present Continuous is used for the actions taking place at the present moment (process)
Present Perfect Simple is used for the actions taking place recently  (result)

Present Perfect Continuous is used for the actions taking place for a long period of time (result+process)

STRUCTURES: 

PS -  am/is/are (если говорим о статусе, состоянии) - I am a teacher. He is a boy. They are students. 

+ verb 1/s  (если говорим об обычных, повседневных делах) - I get up at 7 o'clock.

- don't/doesn't+verb 1

? do/does+verb 1

PC - am/is/are (ситуация на данный момент)+ verb -ing - I am studying English now.

- am/is/are+not

? am/is/are+verb -ing (обратный порядок слов) - Are you travelling down the river?

PPS - have/has + verb 3/ed (важен результат, последствия) - I have already read this book.

- haven't/hasn't+verb 3/ed

? have/has+verb 3/ed (обратный порядок слов) - Have you watched this TV-show?

PPC - have/has been+verb -ing (важен и результат и процесс) - I have been learning  this rule all day.

- haven't/hasn't been+verb -ing

? have/has been+verb -ing (обратный порядок слов) - Have you been practising a lot for the competitions?