问题 问答题 简答题

他励直流发电机和并励直流发电机相比较,短路电流谁大?

答案

参考答案:他励直流发电机的短路电流远远大于并励直流发电机。因为他励直流发电机的励磁与电枢电压无关,发生短路时,电枢电流达到最大值;而并励直流发电机的励磁由电枢电压产生,发生短路时,励磁电流为零,故短路电流由剩磁产生的感应电动势决定,其值较小。

阅读理解

阅读下列短文,从每题所给的四个选项(A、B、C和D)中,选出最佳选项,并在答题卡上将该选项的标号涂黑。

One of the speaking rules you need to know might sound strange to most ESL(English as a second language) students, but it is one of the most important rules. If you want to pass examinations, then study grammar. However, if you want to become fluent in English, then you should try to learn English without studying the grammar.

Studying grammar will only slow you down and confuse you. You will think about the rules when creating sentences instead of naturally saying a sentence like a native. Remember that only a small fraction(部分) of English speakers know more than 20% of all the grammar rules. Many ESL students know more grammar than native speakers. I can confidently say this with experience. I am a native English speaker, majored in English Literature, and have been teaching English for more than 10 years. However, many of my students know more details about English grammar than I do. When they sometimes ask me about grammar, I can easily look up the definition(定义) and apply it, but I can’t tell them the answer off the top of my head.

I often ask my native English friends some grammar questions, and only a few of them know the correct answer. However, they are fluent in English and can read, speak, listen, and communicate effectively.

Do you want to be able to recite the definition of a causative verb(使役动词), or do you want to be able to speak English fluently?

小题1:According to the author, what opinion do most ESL students hold?

A.Grammar matters a lot only in speaking.

B.Grammar doesn’t matter much in speaking.

C.Grammar is not important in English learning.

D.Grammar is very important in English learning.小题2: What is the author?

A.An ESL student.

B.A native English teacher.

C.A native English student.

D.A teacher teaching English natives.小题3: The underlined part “off the top of my head” means ________.

A.without consideration

B.on purpose

C.after thinking

D.with difficulty小题4:Which of the following titles best suits the text?

A.Grammar Counts!

B.Fluency or Grammar?

C.Exams or No Exams?

D.No More Grammar!

判断题