PRESENT TENSE
[ACT]. Suj + V en present tense + Obj;
[PAS]. Obj + V tobe en present tense + part del v pasado
I write the letter; The letter is writen by me
PRESENT CONTINUOUS
[ACT] suj + v en present continuous + obj
[PAS] SUJ + TO BE en present tense + being + par pas v.
I am writing the letter; The letter is being written by me.
PAST TENSE
[ACT] Suj + v en past tense + obj
[PAS] suj + tobe...