what kind of past tense is (it is called..)?

Question

please explain to me...

my teacher told me to write my research in past tense so i followed him.. but when i stated in my research the words:

..a program which is called the inference engine....

he wants it to change the word is to "WAS"....

aren't this statements just the same or not?

Answer 1

"Is called" is not a past tense, despite that "called" looks like a past tense; it is the passive voice. The passive voice is when the subject is acted upon rather than doing the acting.
"A program is called [by people]" is passive. The active form of it would be "people call a program". Notice that "is called" flipped to "call" which is present tense.

Your teacher is right. To keep it in the past tense it should have been "a program was called..." It is good style to keep past or present tense consistent through a piece.

Answer 2

No, they are not the same. You were writing in 'literary present', which is just a really fancy word for things in books (or any writing) being in the present tense. The word "was" in place of "is" means that the program USED TO BE called the inference engine. However, if the name of teh program has not changed, and the program is STILL called teh inference engine, your teacher is WRONG, and you can rub it in their face.

Answer 3

no they are not. if you are supposed to use past tense then WAS is correct. "is" is present tense