a (real) eye-opener

ponaučení, náhlé zjištění něčeho nepředpokládaného

If you feel like it, buy one and have a browse. It can be a real eye-opener to find how many calories there are in the foods you normally eat.

We came together on one point, and that was our attitude towards the media. It had been an eye-opener to me in 1987 when I realized how naïve I had been about the press.

It had been my first alpine climb, and it had been an eye-opener. I had not expected the level of exposure, the narrowness of the arêtes, the commitment.          

(BNC-B)

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