“原形毕露”常见的英文表达有 “be exposed in one's true colors”、“show one's true colors” 或 “the true nature/form is revealed”。以下为你分别举例说明：
“be exposed”表示“被暴露”，“in one's true colors”意思是“以真实面目”，整体强调原本隐藏的真实面目被揭露出来。
例句：Once faced with the real challenge, his incompetence was exposed in his true colors. 一旦面临真正的挑战，他的无能就原形毕露了。
“show”有“展示、显现”之意，“true colors”指“本色、真面目”，该短语侧重于主动或自然地展现出真实的自己或情况。
例句：After a few drinks, he started to show his true colors and became very aggressive. 喝了几杯酒后，他开始原形毕露，变得非常咄咄逼人。
这是一种比较直白的表达，“the true nature/form”指“真实的本质/形态”，“is revealed”表示“被揭示”，直接说明了原本隐藏的东西被展现出来。
例句：When faced with pressure, the true nature of the company's management was revealed. 在面临压力时，公司管理层的真实面目原形毕露了。