after it/what seems to be a long time,he came up.

what seems to be a long time = something that seems to be a long time
过了某种似乎是很长时间的东西,其实就是很长时间它本身啦.
Give me what is the best=Give me something that is the best.
给我某种最好的东西,其实就是给我最好的东西啦.
前句是名词性从句来,后句是定语从句来的.
用it的话你要注意seem这个词哦.就是翻译成中文也说不通的.