请教一个关于时际替代效率和时内替代效率的问题：

大家帮我分析分析下面一端话：

With the assumption of the Cobb-Douglas preferencec in consumption, two goods are complements when the elasticity of intertemporal substitution is larger than the elasticity of intratemporal substitution.

出自一篇研究国际货币政策的文章

Many thanks!!!!!!