catch sb on the wrong foot 令（某人）措手不及，在不适宜的时候让做某事

【例句】
I hadn't expected the question and it caught me on the wrong foot.
我没有预料到这个问题，它使我措手不及。

The COVID-19 spread quickly and caught many countries on the wrong foot.
新冠的爆发，让很多国家措手不及。