一気 Kanji
彼は一気に10時間働いた。 He worked ten hours at a stretch.
一気飲 Kanji
一気呵成 Kanji
彼、一気呵成に書き上げたと言ってたけど、この提案書、少し雑だね。 He said he dashed this proposal off in one sitting. It's pretty sloppy.
一気飲ッ Kanji