原因、结果

• because, as, for, since这几个词都是表示“原因”的连词，语气由强至弱依次为：because→since→as→for; 其中because, since, as均为从属连词，引导原因状语从句；而for 是并列连词，引导并列句。
• for用作连词时，与because相似。当for引导原因状语从句时：并不一定说明主句行为发生的直接原因，表示附加或推测的理由，for引导的原因状语从句只能放于主句之后（不可置于句首），且必须用逗号将其与主句隔开，for的这一用法常用在书面语中，较正式。

1. The book remains at rest or, in physical terminology, in static equilibrium not because there are no forces acting on it but because the forces which do act on it annul one another. 此书处于静止，或者用物理术语来讲处于静力平衡，并不是因为没有力作用在它上面，而是因为作用其上的力彼此互相抵消。
2. As friction is always present, it naturally causes losses in all types of machines, since because of friction; part of useful mechanical energy is lost in the form of useless heat. 由于摩擦总是存在，所以很自然，部分有用的机械能会因摩擦以无用的热的形式失去，所以摩擦使所有的机器均产生（能量）损失。 
3. Theoretically at least we should be able to copy these mechanisms found in nature, for all biological organisms are in part actually electrical systems. 至少在理论上我们应该能够模仿在自然界发现的这些机制，因为在所有生物组织中有一部分实际上是电系统。 
4. The output power can never equal the input power, for there are always losses. 输出功率决不可能等于输入功率因为总有损耗。 （此处for=becasue）
5. The decrease in intensity due to absorption is called damping and a wave whose intensity decreases for this reason is called a damped wave. 由于被吸收而强度减低叫做阻尼，而由于这一原因其强度减小的波叫做阻尼波。
6. For reason given above the scheme should be redesigned. 鉴于上述原因，此方案应重新设计。
7. for reasons of what follows 鉴于一下原因； for reasons soon to become obvious 鉴于很快见诸下文的原因；