Never stop smiling, not even when you are sad, someone might fall in love with your smile.
永远都不要停止微笑，即使是在你难过的时候，说不定有人会因为你的笑容而爱上你。

protest against sth 抗议

against sth provision for/against 准备

pull at/on sth 拉,拖

ratio of sth to sth 比率

reaction to 对……的反应

reason for 原因,理由