2 sentences

1. 边际效用递减是经济学的一个基本规律。

   biān​jì xiào​yòng dì​jiǎn shì jīng​jì​xué de yī gè jī​běn guī​lǜ.

   Diminishing marginal utility is a fundamental law of economics.

   Source: Dong Chinese Dictionary

2. 这种新工具在野外生存中具有很高的效用。

   zhè zhǒng xīn gōng​jù zài yě​wài shēng​cún zhōng jù​yǒu hěn gāo de xiào​yòng.

   This new tool is highly useful for wilderness survival.

   Source: Dong Chinese Dictionary