بله جمله مجهول است. فاعل (کننده کار) جمله پلتفرم نیست, بلکه پروسسور هست.
دیفایند فعل هست. البته در بعضی از جاها گذشته کامل یک فعل میتونه صفت باشه. اینجا نیست.
a platform is defined by a processor.
a processor defines the platform.
پلتفورم توسط پردازشگر تعریف میشود/ تعریف شده است
پردازشگر پلتفورم را تعریف میکند
مثال های بیشتر برای مجهول و معلوم active & passive
present simple
I make a cake.
A cake is made (by me).
present continuous
I am making a cake.
A cake is being made (by me).
past simple
I made a cake.
A cake was made (by me).
past continuous
I was making a cake.
A cake was being made (by me).
present perfect
I have made a cake.
A cake has been made (by me).
pres. perf. continuous
I have been making a cake.
A cake has been being made (by me).
past perfect
I had made a cake.
A cake had been made (by me).
future simple
I will make a cake.
A cake will be made (by me).
future perfect
I will have made a cake.
A cake will have been made (by me).