- Business consultation
- Business meetings and professional conventions and conferences
- Buy materials and goods
- Contract negotiation
- Take on independent research
- Take part in court trails as witness
- Undergoing medical treatment
- Participating in conferences, conventions and conferences of social organizations
- Visiting family and friends
- Typos or mistakes in the U.S. visa application form
- Incomplete application form
- Discrepancies in the documents submitted
- Providing falsified information
- Criminal records of any sort
- Lack of enough funds
- Previous history of violating the immigration rules