问题 填空题

一般来说,男同学讲话的______ 比女同学低,是因为男同学声带振动的______ 。一个同学大声说话和小声说话主要是他声音的______不同,这是因为他声带振动的______不同。

答案

音调;频率低;响度;幅度(振幅)

男同学比女同学讲话比较低沉,音调比较低,是因为男同学声带振动频率低.

大声说话比小声说话声音大,响度大,是因为大声讲话的同学声带振动幅度大.

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     People who are concerned about pollution will be happy to know that clean and renewable energy sources

that protect the environment such as solar energy are becoming possible alternatives.

     Increasing demand for clean, renewable energy is driving a growing market for solar energy products..

Two of the main types of products that take advantage of solar energy are passive and active solar products.

These two types of systems differ in how they are constructed and can also differ greatly in cost. Passive solar

technology can be used to heat air or water directly using the sun's energy. Unlike an active solar application,

passive solar set-ups accomplish their task without the use of additional electrical components, such as fans

that need an external electricity supply. Some solar space heating or water heating systems are active solar

heating systems that have various components that call for external power sources. Because of their simplicity

compared with active systems, passive solar heating systems generally are cheaper than active ones.

     In addition to these solar heating systems, there are also solar power system available. Rather than using the

sun's energy for heating applications, these systems change solar energy into electricity. An important part of

these products is called photovoltaic cells, which generate electricity from light. As sunlight falls on a

photovoltaic cell, the light's energy is changed into electricity that can then be used to power many kinds of

electronic devices. Because of the complicated technology involved, these kinds of solar power systems can

be very expensive.

     When considering what kind of solar heating or power system to install (安装) in your home or business,

be sure to purchase your equipment from a reputable manufacturer who will be able to help you with any

necessary repair.

                                                          Solar energy application