Past simple, Present Perfect simple and continuous

Past simple / Present Perfect simple
Past simple / Present Perfect simple
Past simple / Present Perfect simple
Past simple / Present Perfect simple
Present Perfect / Present Perfect Continuous
Present Perfect / Present Perfect Continuous

Passive - Present/Past simple

Passive voice is used when the focus is on the action; it's not important or not known who or what is performing the action:

. We use an active verb when we say "what the subject does"
                       My father built this house the last year.
  We use a passive verb when we say "what happens to the subject"
                       This house was built the last year.


. When we use passive, who or what causes the action is often unknown or unimportant.
                     Active:     Somebody stole my bike.
                     Passive:   My bike was stolen.


. Present Simple: 
                   Active:  clean(s), see(s),watch(es)......
                               Somebody cleans this room every day.
                   Passive:  am/is/are + cleaned /seen/ watched......
                                                     ( past participle (regular verbs+ed
                                                       irregular verbs 3rd column))
                              This room is cleaned every day.
                              I'm not often invited to parties.
                              
. Past simple:

                  Active:  cleaned, saw, watched......
                               Somebody cleaned this room yesterday.
                   Passive:  was/were + cleaned /seen/watched......
                                                     ( past participle (regular verbs+ed
                                                       irregular verbs 3rd column))
                              This room was cleaned yesterday.
                              When I was fifteen, I wasn't invited to parties.


Practice:
Ejercicio 1 - Present Simple

Ejercicio 2 - Past simple

Ejercicio 3 - Present simple

Ejercicio 4 - Past simple 

Ejercicio 5 - Present simple

Ejercicio 6 - Past simple