频繁使用使剪刀的锋利度降低了。

Frequent use has ___blunted the scissors' sharpness.

长期吸烟削弱了他的味觉敏感度。

Years of smoking have ___blunted his sense of taste.

长期使用止痛药使他对疼痛的感知变得迟钝。

Long-term use of painkillers has ___blunted his sensitivity to pain.