He's not with it. 他无法领悟话中的意思. He has no clue. 他懵懵懂懂, 不晓得自己在做什么. The driver has many things on his mind. 这个司机驾车心不在焉.
He got lost in the shuffle. 他迷失在困惑里. Wake up and smell the coffee. 清醒过来, 认清现状.
He doesn't know what's going on. 他对现况茫无所知. He's totally lost. 他已全然迷失.
Hey, snap out of it! 嘿, 清醒点儿! Pal, you're in for a rude awakening. 老兄, 你美梦快破碎了.
