正确答案: A

珍珠岩

题目：在常温和低温条件下，使用效果较好的隔热材料有( )。

解析：A

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举一反三的答案和解析：

[单选题]第一组An automatic system usually consists of a control system and an information system. A control system is a system which measures the condition of some entity and, with the information, governs the state of a variable; i.e., speed, temperature, pressure, position, etc. The open-loop system is the simplest form. a control system may assume. It is distinguished from the closed-loop system by the lack of an input which measures the state of the controlled variable; such an input is called a feedback. In modern ships the open-loop system has practically disappeared and the closed-loop system which operates with a feed-back is extensively used. An information system serves the parallel function of monitoring system or plant performance. The monitoring function may serve a number of purposes; specifically it may indicate values of controlled variables to guide remote control operations, warn of off-limit conditions and provide record of performance. In many cases a visual and audible alarm may be provided to warn of off-limit conditions on board ship and, associated with this, the important variables will be recorded on demand. The automatic control system can be more sophisticated by incorporating digital-processing equipment, that is, a computer. This computer is usually fed with signals from all sensors. It scans the values of the sensors and generates alarm signals for off-limit conditions, acting as a super-supervisor. Sometimes, it can even make necessary and take the necessary action to optimize performance without human intervention.

the presence of a feed back

[单选题]我国《海船船员值班规则》对在港船舶轮机值班人员组成规定：推进功率为______及以上的船舶，必须安排至少______机工协助值班轮机员值班。

750kW/1名

[单选题]部分封闭式救生艇的结构特点是（）

便于登乘、操作、避免了人员暴露、倾覆后人员不易逃离