1.2专业英语的基本特点 为了了解专业英语的特点,我们先阅读下面一段关于许用应力的课文 Despite the tests described in Chapters 1l and 12, materials may still fail in service, sometimes with disastrous results (e.g. when the failure occurs in aircraft. bridges, ships, etc. ) To try to avoid such disastrous occurring, the designer avoids using materials continuously at their maximum allowable stress. This is done by employing a factor ot satety Unfortunately, increasing the strength of a component in the interests of safety not only increases the initial material costs, but also the operating costs. For example, the stronger and heavier the structure members of an aircraft, the fewer passengers it can carry and the more fuel it consumers. Therefore a balance has to be maintained between safety, initial cost and operating costs. The designer is constantly striving to improve the former whilst reducing the latter.1.2 专业英语的基本特点 为了了解专业英语的特点，我们先阅读下面一段关于许用应力的课文。 Despite the tests described in Chapters 1l and 12，materials may still fail in service，sometimes with disastrous results (e.g. when the failure occurs in aircraft．bridges，ships，etc.). To try to avoid such disastrous occurring，the designer avoids using materials continuously at their maximum allowable stress. This is done by employing a factor of safety. Unfortunately，increasing the strength of a component in the interests of safety not only increases the initial material costs，but also the operating costs. For example，the stronger and heavier the structure members of an aircraft，the fewer passengers it can carry and the more fuel it consumers．Therefore a balance has to be maintained between safety，initial cost and operating costs．The designer is constantly striving to improve the former whilst reducing the latter．