H-1B 為期一年的延期, 或3年延期?

我一直在H-1B, 五年了. 我知道, H - 1B可以延長到六年限製, 並有一個為期一年的延期，另一種方式就是3年延期。What is the requirement to get H-1B 為期一年的延期, 或3年延期？

Answer:  USCIS has interpretation of the H-1B rules in favor of the H-1B holders, allowing the H-1B holders to maintain the H-1B status beyond six-year limit without jeopardizing their immigration process. The AC21 rule allows H-1B extension in three-year increments beyond six year limit, if you have form I-140 petition approved and the immigrant visa number is not available for you in the Department of State's Visa Bulletin. 

The AC21 also allows H-1B holders to apply for H-1B extension beyond the six year limit in one-year increments, if the your Labor Certification has been pending longer than 365 days before reaching 6th year of your H-1B, to be qualified for initial 7th year extension of H-1B status. (see www.greencardapply.com/question/question07/question07_0110.htm)