Can an illegal alien work in the US without a green card or visa?

Answer

Not legally, no. Do you have family in the US legally? Do you have a potential employer in the US? Are you an engineer, doctor, etc? You could apply for entry and residence based on these (essentially you need a sponsor for the first 2). You should be able to apply for a work card when you apply for adjustment of status. (seeking permanent residency).

Answer

That's right, by law it's illegal. But they do work anyway. Either they get pay cash only or the work with a fake "green card" and Social security number. They take their chances because the option is not pretty neither, I mean, they would not have any money to live by.

Answer

Be aware if you work on forged documents you're not only doing something illegal, you're causing your employer to break the law. Many illegal immigrants don't understand why their employers aren't more helpful. It's because the fine for employing an illegal immigrant -- even unintentionally-- is up to $100,000 per person.

Answer

Yes they can though its illegal they get jobs the dont requires documents like lawn service and other types of jobs normally they get paid under the table but perhaps wont get as much as any legal person would.