stimulant|stimulants

这杯咖啡是我早上的提神剂。

This cup of coffee is my morning ___stimulant.

新鲜的空气和阳光是最好的提神剂，能让人精力充沛。

Fresh air and sunshine are the best ___stimulants to keep you energized.

新推出的教育政策对学生的学习热情起到了激励作用。

The new education policy served as a ___stimulant for students' learning enthusiasm.