What tense is this?

It may be passive.

http://www.englishpage.com/verbpage/activepassive.html

"Happens" and "is" are simple present. "Finished" is a nominal (noun) here. You can replace it with "done" or others nouns meaning "to end". "[blank] is finished/done/brought to an end."

And "is" notes the passive voice because "[what] is finished [by] [what]".

'Maybe nothing happens once and is finished.'

"Nothing" is the subject. "Happens" is the predicate (verb). "Is" is present tense, and I would say that "finished" is an adjective describing "nothing."

The_Ink_Goddess said:

It's a verb, right? What kind of verb form?

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past participle (they like to behave like adjectives, naughty things)

Finished is a participial - an adjective of the nature of a participle. A participle is a form of the verb expressing tense and voice in conjunction with an auxiliary such as, in this case, the verb to be.

It's present tense. The same form of the verb sometimes has different usages, like

I solved the problem. - past
I have solved the problem. - present perfect
The problem is solved. - participial
The problem is solved by combining like terms and dividing by the coefficient of x. - passive

All but the first of these are present tense, like your example, even though the main verb looks like a past tense verb.

morngnstar said:

It's present tense. The same form of the verb sometimes has different usages, like

I solved the problem. - past
I have solved the problem. - present perfect
The problem is solved. - participial
The problem is solved by combining like terms and dividing by the coefficient of x. - passive

All but the first of these are present tense, like your example, even though the main verb looks like a past tense verb.

Click to expand...

Present perfect is the perfect tense, which is one of the everal past tenses.