是移民局要求的吗?
No. It's not necessary. It's just one of the evidences of your language efficiency. You will possibly be exempted from it if you get a degree from a U.S. college.
能加快审理速度吗?
I don't think so. Unlike H-1 visas in U.S. there is no such a thing as paying extra to speed up the application process even if you allow an immigration attorney to proceed your case.
还有,办fbi的无犯罪证明需要多久?
About two or three weeks.
一般情况下受到第二封信后多久能拿到枫叶卡?-可以通过申请。
The timeline sregarding it vary from case to case and it also depend on how many applicants. In current situation, it may take about 1-2 years after second letter.
谢谢大家了!!!!!
Good luck !