我以前解釋過牽引的作用原理。你現在的情況應該有用。

來源: 薛成於 2015-09-25 16:42:17 [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次

WENXUECITY.COM does not represent or guarantee the truthfulness, accuracy, or reliability of any of communications posted by other users.