嗯，这朋友搬走也不说一声也挺奇葩的

前年。。。元旦。。。去年夏天，住了一年多了吧

不知你具体指什么，愿闻其详。

我查了下，觉得楼主儿子不能在朋友餐馆里打工，不拿钱也不行。

Exchange students traveling to the United States to participate in an exchange program need an exchange visitor visa, also known as a J-1 visa.

J-1 visa holders can work off campus in certain circumstances: 

• Economic hardship
• J-1 students may be eligible for off-campus work authorization if they are facing severe economic hardship. The circumstances must be unexpected and beyond their control. 
• Related to their major
• Off-campus employment may be authorized if it''s directly related to the student''s major field of study and enhances classroom learning. 
• Practical training
• Responsible officers may authorize J-1 students for practical training, which includes paid off-campus employment and/or unpaid internships.

J-1 visa holders can volunteer without work authorization if they meet certain criteria, but most other work requires work authorization, whether it''s paid or unpaid: 

• Volunteering
• J-1 visa holders can volunteer if their activities meet the definition of volunteering, such as: 
• Taking a shift at a food bank 
• Donating time with the American Red Cross 
• Serving at a homeless shelter 
• Walking dogs at an animal shelter 
• Building for Habitat for Humanity 
• Other work
• J-1 visa holders need work authorization for most other work, whether it''s paid or unpaid. This is because the U.S. Department of Labor wants to protect jobs for U.S. citizens and prevent worker exploitation.