他紧张时不停抖腿的小动作是个明显的破绽。

His constant leg shaking was a ___telltale sign of nervousness.

那个告密者向老板透露了同事的计划。

The ___telltale revealed his colleague's plan to the boss.

引擎发出的奇怪噪音是机械故障的明显征兆。

The strange noise from the engine is a ___telltale sign of mechanical problems.