Investors from all over the world can buy project tokens?

Yes, no limitations.

Before buying a token, do investors need to go through the verification process?

Yes, you're right. KYC is obligatory.

Can it be that the investor will not pass the test? Then how to become your sponsor?

Not pass? What does not pass in the profession of an investor?
And how to become a sponsor is to support the project Airchain campaign bounty.

AnnaJames12