一体 => …the heck; …in the world; …on earth N3
を中心に => focused on; centered on~ N2
も同然 => just like; same as ~ N2
一緒に => together N5
一度に => all at once N3
と同時に => at the same time as; while; simultaneously ~ N2
一通り => Basically, (get) over, done N2
Base, base
[中心「ちゅうしん」]に => With A as the center N2
Miscellaneous
一方だ => more and more; continue to ~ N2
~もどうぜんだ(~も同然だ)      => just like; same as ~ N1
一応 => more or less; pretty much; roughly; tentatively ~ N2
一方 => on one hand, on the other hand; although ~ (conjunction) N2