to do a U-turn 来一个180度大转弯

在驾驶时，U-turn 就是来一个180度的大转弯或调头。在现实生活中，这个短语的意思是形容对某事的态度或观点来了一个180度的大转弯，彻底改变。

例句

I'm afraid your father has done a U-turn and he won't let you take his car at the weekend after all.

The university did a U-turn and decided not to expel the student.

请注意

另一个常用成语“at a crossroads 在交叉路口或十字路口”可以用来形容紧要关头，需要做出关键决定的时刻。

例句

You're at a crossroads now. You need to decide what you want to study. Arts or sciences?

Their marriage was at a crossroads. They could either try again to make it work or take the decision to split up.