Each macronutrient yields a different relative number of calories.

每种常量营养素产生不同的卡路里相对数量。

By then it had yielded a number of lessons.

到那时, 它已经产生了许多教训。

What you need to see is that the quotient on the right must always yield the same number because it's a constant.

你需要看到的是右边的商必须总是产生相同的数字， 因为它是一个常数。