您好，在您原文的基础上修改如下，不明白可继续提问： When I registered this new semester in Fall 2013, I have paid the register fee online, but I don't know why I have paid $30 dollars twice. I remembered clearly that I paid the register fee right after I filled out the forms of Dawson, but the second time I paid the money was on my portal, as it said...
