was/were

somebody was correct.
were is used for plural.

was is used thusly --

A single sedan was parked on the top floor.

region is correct Yoong

Re: was/were
Nothing always takes a singular verb. It is a conjunction of "no" and "thing". So you can't use "minivans" in the plural.

Nothing but a minivan was parked on the top floor.

Only minivans were parked on the top floor.

Indefinite pronouns by definition reference nonspecific things or people. Most of these pronouns take a singular verb, some are always plural, and a few may be either singular or plural. Most indefinite pronouns are singular.

Singular:

another, anybody, anyone, anything, each, either, everybody, everyone, everything, many a, neither, no one, nobody, nothing, one, other, somebody, someone

Plural:

both, few, many, others, several

Singular or Plural:

all, any, none, some, such

Hi Contrex

Nothing but buses was/were parked on the top floor.

I think 'was' should be used.

Nothing was parking on the top floor but/except buses.

Am I right? Or should it be Nothing but a bus was parked. But I'm referring to buses, not one bus.

Many thanks.

As I wrote, "nothing" needs a singular verb. If you are referring to buses in the plural, write "Only buses were parked on the top floor".

Thanks, Contrex.

Re: was/were