在软件开发里，程序员编写前置和后置条件来确立特定软件组件的角色。
In software development, the programmer writes pre - and postconditions in order to establish the role of a particular software component.
后置条件测试确保组件完成操作的时候结果符合要求，假设前置条件已经满足。
Postcondition tests are guarantees that the component promises to satisfy when it completes the operation, assuming the preconditions are met.
耳机组件和前置摄像头也需要占用空间。
The earphone component and the front camera also take up space.
对组件输入(例如传递给方法的参数)的测试叫做前置条件测试。
Tests on component inputs (such as parameters passed to methods) are called precondition tests.
前置放大器是光接收机前端中最重要的组件之一，它直接影响光接收机的速度、噪声、灵敏度等整体性能。
Preamplifier is one of the most important components in photoreceiver front-end. It directly affects the performance of light receivers such as speed, noise and sensitivity.
前置放大器是光接收机前端中最重要的组件之一，它直接影响光接收机的速度、噪声、灵敏度等整体性能。
Preamplifier is one of the most important components in photoreceiver front-end. It directly affects the performance of light receivers such as speed, noise and sensitivity.
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