flinch|flinched|flinches

看到蜘蛛时，她不禁畏缩了一下。

She couldn't help but ___flinch at the sight of a spider.

看到蛇时，他吓得往后一缩。

He ___flinched when he saw the snake.

她面对挑战从不退缩，总是迎难而上。

She never ___flinches from challenges, always facing them head-on.