请问签H-1B都需要什莫材料，谁能给个单子或连接？我查了半天也没找到有用的信息，还是很confuse

http://www.usembassy-china.org.cn/visa/hlopq.html

这是我找到的网址。
“It is also advised that all applicants bring to the interview a certified copy of the I-129 application material.“ 啥叫certified copy of the I-129， 我们不就一份I-129表吗？

谢谢点拨！