断路器“跳跃”现象一般是在跳闸、合闸回路同时接通时才发生，防_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题判断题

断路器“跳跃”现象一般是在跳闸、合闸回路同时接通时才发生，防跳回路的设计应使得断路器出现跳跃时将断路器闭锁到跳闸位置

答案

参考答案：对

解析：

知识点：二次回路

填空题

Part 3

Questions 19-25

·Read the following passage and answer questions 19-25.
·For questions 19-25, choose the correct answer from A, B, C and D.
·Mark your answer on the Answer Sheet.
The number of speakers of English in Shakespeare’s time is estimated to have been about five million. Today it is estimated that some 260 million people speak it as a native language. Mainly in the United States, Canada, Great Brittany, Ireland, South African, Australia and New Zealand. In addition to the varieties of English found in these areas, there are great many regional and social varieties of the language, as well as various levels of usage that are employed both in its spoken and written forms.
It is virtually possible to estimate the number of people in the world who acquired adequate work knowledge of English in addition to their own languages. The purpose for which English is learned and the situation in which such learning takes place are so varied that it is difficult to define and still more difficult to assess what constitutes an adequate working knowledge for each situation.
The main reason for the widespread demand for English is its present-day importance as a world language. Besides serving the infinite needs of its native speakers, English is a language in which some of the most important works in science, technology, and other fields are produced and not always by native speakers. It is widely used for such purpose as meteorological and airport communications, international conferences, and the spread information over the radio and television networks of many nations for the number of developing countries, especially former British colonies. Many of these countries have multi-lingual populations and need a language for internal communication as well as for international communication and for access to the scientific and technological development in the west.

According to the passage, which of the following statements is NOT true

A．Some 260 million people in the word have an adequate working knowledge of English.

B．There are some 260 million native speakers of English in the world.

C．It is also impossible to estimate the number of people with an adequate working knowledge of English.

D．People learn English for variety of reasons.

解答题

试一试：将7400克、800千克、8070克、9千克、8千克6克按从大到小的顺序排列______．