他似醒非醒。

He hovered on the edge of consciousness.

《牛津词典》

提阿非尔看上去悲伤而如梦似幻，没有和任何人说话。

Theophile looked sad and dreamy, and didn't talk with anybody else.

youdao

看门人半露出身子，打着呵欠，似醒非醒，手中拿着蜡烛。

The porter half made his appearance yawning, vaguely awake, and with a candle in his hand.

youdao

The leaves are about to fall but they haven't yet fallen.

这些叶子似坠非坠。

耶鲁公开课 - 弥尔顿课程节选

But I think this is rather an implausible suggestion because, of course, you could have these glorious views just by going up in the airplane and looking down from the safety of your airplane.

但我认为这是个似是而非的建议,因为，当然，你可能只是坐飞机向上飞,并安全地向下看,就会有这些迷人的视野。

耶鲁公开课 - 死亡课程节选