主页
学科
搜索
账户
常见问题
当前学科：中级钢轨探伤工
题目：
问答题
何谓超声波？它有哪些重要特性？
答案：
<查看本题扣1积分>
查看答案
答案不对？请尝试站内搜索
推荐知识点:
根据下列短文，回答题。 There are various in which individual economic units Can interact with one another．Three basic ways may be described as the market system，the administered system and the traditional system．In a market system individual economic units are free to interact among each other in themarketplace．It is possible to buy commodities from other economic units or sell commodities tothem．In a market，transactions may take place via barter or money exchange．In a barter economy，real goods such as automobiles，shoes and pizzas are traded against each other．Obviously，finding somebody who wants to bade my old Car in exchange for a sailboat may not always bean easy task．Hence，the introduction of money as a medium of exchange eases transactions considerably．In the modern market economy，goods and services are bought or sold for money． An alternative to the market system is administrative control by some agency over all trans．actions．This agency will issue edicts or commands as to how much of each good and service should be produced，exchanged，and consumed by each economic unit．Central 01anaing may be one way of administering such an economy．The central plan，drawn up by the government,shows the amounts of each commodity produced by the various firms and allocated to differenthouseholds for consumption．This is an example of complete planing of production，consump—tion，and exchange for the whole economy． In a traditional society，production and consumption paUerns are governed by tradition：everyperson’S place within the economic system is fixed by parentage，religion and custom． Transac—tions take place on the basis of tradition，too．People belonging to a certain group or caste mayhave an obligation to care for other persons，provide them with food and shelter，care for theirhealth，and provide for their education．Clearly，in a system where every decision is made on thebasis of tradition alone，progress may be difficult to achieve．A stagnant society may result．What is main purpose of the passage?
同时断定“只有P，才Q”与“非P并且Q”两个判断为真，是否违反普通逻辑基本规律？若违反，则违反了什么规律？为什么？
自我决定理论则认为，个体的行为或学习成绩是()，个体能够改变自己的命运
我国和大部分国家的气缸号的排号都采用从（）设置数起。
设备监理工程师审核总承包商提交的设备采购计划时应注意的内容是（ ）。
不属于民法的具体表现形式的是()。
最高工作温度95ºC时载流量≥（）A。
除下列哪项外均可引起面肌痉挛（）
超声波探伤时施加耦合剂的主要原因是（）。
查明当事人的演出经纪活动是否规模较大或者社会危害严重是查处“擅自设立演出经纪机构”案件的取证要点之一。（）