1·Hence, validation can entail a large performance cost if a validating processor needs to parse and build an in-memory representation of a schema before validating each XML document.
因此，如果在验证每个XML文档之前，都要构建模式的内存中表示，验证可能造成很大的性能代价。
2·Guarantees are popular because they entail no immediate cost.
担保之所以受到如此偏爱，是因为它并不产生即刻的花费。