The industry use background, industry policy, qualification management, technical principle, installation requirements, working manner and application prospect of household gas alarm are described.
论述了家用燃气报警器的行业使用背景、行业政策、资质管理、技术原理、安装要求、工作方式、应用前景。
About the qualification of witness, the basic principle is every one has qualification except for some special status what is described clearly in the witness law.
证人资格方面，以任何人拥有证人资格为一般原则，由法律明确规定例外情况。
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