他一点一点地掌握了这项复杂的技能。

He mastered the complex skill ___bit ___by ___bit.

这座古堡在几十年间被一点一点地修复。

The ancient castle was restored ___bit ___by ___bit over decades.

这项新政策的影响将在全国范围内逐渐显现。

The new policy's effects will be felt ___bit ___by ___bit across the nation.