Instead of running all your automated unit tests every day, only run the ones that need to pass for this particular delivery or iteration.
不必每天运行所有自动化的单元测试，而只运行此特定交付或迭代需要通过的测试。
2
While your personal computer only keeps one copy of a file, large-scale services like Facebook rely on what are called content delivery networks to manage data and distribution.