在经济学课堂上，我们学习了凯恩斯对政府干预经济的理论。

In economics class, we studied ___Keynes's theories about government intervention in the economy.

凯恩斯主义政策主张在经济低迷时期通过财政刺激来提振需求。

___Keynesian policies recommend fiscal stimulus to boost demand during economic downturns.