父母是以探亲签证类型进入美国，我将于下个月进行公民面试并打算帮他们申请美国绿卡。想请问大家，我帮他们递交申请绿卡的表格时需要递交I-131表格吗？
如果需要递交，那么表格中
1.Part 1: Information about you 中第3项class of admission 应该怎么填？
2.part5:Complete only if applying for a reentry permit:Since becoming a permanent resident of the United States (or during the past five years, whichever is less) how much totoal time have you spent outside the United States?这栏该怎么填？父母两年前来过美国并待了6个月，也就是说在过去的5年里面有大于4年的时间是在国内，那么我是否应该选择：more than four years?
先谢谢大家，期待各位能给予指点。多谢！