频繁使用让剪刀的刀刃变钝了。

The scissors' edge became ___dulled from frequent use.

长期的压力使他对生活中的小乐趣变得麻木。

Constant stress has ___dulled his sensitivity to small joys in life.

频繁洗涤使得这件红色毛衣的颜色变得暗淡了。

Frequent washing has ___dulled the color of this red sweater.