Since it is not possible to sum target fields into another target field, we need to sum and multiply the source Price fields into the target Amount field. The XPath expression looks like this.

因为不可能将目标字段的和作为另一个目标字段的值，所以我们需要求和，并乘以源price字段，作为目标amount字段的值。

youdao

And I will multiply the fruit of the tree, and the increase of the field, that ye shall receive no more reproach of famine among the heathen.

我必使树木多结果子，田地多出土产，好叫你们不再因饥荒受外邦人的讥诮。

youdao

Just as medicine has become a highly specialized field, the specialties for medical assistants continue to multiply.

正像医学已经变成了一个高度专业的领域，医疗助理的专业也变得多样化了。

youdao

Nationwide, the arguments for teams to be able to "prove it on the field" will annoyingly multiply.

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