我新的锻炼计划一个受欢迎的副作用是睡眠质量显著改善，压力水平降低。

A welcome ___side ___effect of my new exercise regimen has been significantly improved sleep quality and reduced stress levels.

这项经济政策一个严重的副作用可能是贫富差距的进一步扩大，这并非政府的初衷。

A serious ___side ___effect of the economic policy could be a further widening of the wealth gap, which was not the government's original intention.

社交媒体广泛普及一个未预见到的副作用是对青少年心理健康和社会发展的深远影响。

One unforeseen ___side ___effect of the widespread adoption of social media is its profound impact on adolescent mental health and social development.