求翻译，要准确，把因为翻译为中文，不要要软件翻译。这是有关化工专业英语的。

1.、All fluids are compressible - even water - their density will change as pressure changes. Under steady conditions, and provided that the changes in pressure are small, it is usually possible to simplify analysis of the flow by assuming it is incompressible and has constant density.2、In a region such as outer space, which is virtually void of gases, the pressure is essentially zero. Such a condition can be approached very nearly in a laboratory when a vacuum pump is used to evacuate a bottle. The pressure in a vacuum is called absolute zero, and all pressures referenced with respect to this zero pressure are termed absolute pressures. Many pressure-measuring devices like the manometer measure not absolute pressure but only difference in pressure. The reference pressure is actually the atmospheric pressure. Whenever atmospheric pressure is used as a reference, the possibility exists that the pressure thus measured can be either positive or negative. When this difference is positive, this type of pressure reading is called gage pressure.3、The term “chemical engineer” implies that the person is primarily an engineer whose first professional concern is with manufacturing processes— making something, or making some process work. The adjective “chemical”implies a particular interest in processes which involve chemical changes.4、While technical advances and efficiency improvements in specific unit operations are occurring the time, the big story is the hybridization of processes. Combining individual unit operations, such as reaction, and heat exchange, into larger, concurrent operations will be major trend om upcoming years. Technologies such as reactive distillation, catalytic membranes, and phase-transfer catalysts all represent examples of hybridized processes where reaction and separation are combined.5、The unit operations are largely used to conduct the primarily physical steps of preparing of reactants, separating and purifying the products, recycling unconverted reactants, and controlling the energy transfer into or out of the chemical reactor. We also can say that, the unit operations deal mainly with the transfer and change of energy and the transfer and change of materials primarily by physical means but also by physical-chemical means.6、Unlike many products whose structure and reactions were well known before their industrial application, some polymers were produced on an industrial scale long before their chemistry or physics were studied.7、Configurational isomerism is then due to the presence in the molecule of one or more dissymmetric centers, in the simplest case asymmetric carbon atoms each of which can have (R) and (S) absolute configuration; and, or, to the presence of double bonds which can give cis- and trans-geometrical isomers.8、The homologes of benzene are those containing an alky group or alkyl groups in place of one or mote hydrogen atoms.