这场灾难清楚地证明了需要更严格的控制。

This disaster is a clear ___demonstration of the need for tighter controls.

女性普遍穿裤子证明了社会角色的变化。

Most women wearing trousers is a ___demonstration of changing social roles.

这些数据有力地证明了新疗法是有效的。

The data provides a convincing ___demonstration that the new treatment is effective.