happen -> случаться
Образование времен (Действует субъект! - Актив т.е. действительный залог):
  Past - ПрошлоеPresent - НастоящееFuture - Будущее
Simple - Факт
I/he/she/it/we/you/they
happened
did happen
----
did not happen
did'nt happen
I/we/you/theyhe/she/it
happenhappens
do happendoes happen
----
do not happendoes not happen
do'nt happendoes'nt happen
I/he/she/it/we/you/they
will happen
 
----
will not happen
won't happen
Continous - процесс
I/he/she/itwe/you/they
was happeningwere happening
----
was not happeningwere not happening
Ihe/she/itwe/you/they
am happeningis happeningare happening
----
am not happeningis not happeningare not happening
 is'nt happeningare'nt happening
I/he/she/it/we/you/they
will be happen
----
will not be happen
won't happen
Perfect - Завершенность
I/he/she/it/we/you/they
had happened
----
had not happened
had'nt happened
I/we/you/theyhe/she/it
have happenedhas happened
----
have not happenedhas not happened
haven't happenedhasn't happened
I/he/she/it/we/you/they
will be happened
----
will not be happened
won't be happened
Perfect Continous - Процесс в периоде
I/he/she/it/we/you/they
had been happening
I/we/you/theyhe/she/it
have been happeninghas been happening
I/he/she/it/we/you/they
will have been happening
happen -> случаться