官网上提到 A letter from the applicant’s employer granting leave of absence and stating how long the applicant has been employed, his/her designation and salary if he/she is employed; or A copy of the household booklet if he/she is a PRC national and is unemployed. 这是个什么样的东西,大家都有提交么?我父母一方已退休,一方未退休,且均未60周岁。不知道该提交什么材料呢?