问题 单项选择题

激励器的作用有()。①用来产生具有所需工作种类的信号;②产生发射所需频率的信号;③用来放大射频信号,以达到额定的输出功率;④产生单边带信号,再将它线性地搬移到发射频率范围内

A.①②④

B.①③④

C.①②③

D.②③④

答案

参考答案:A

阅读理解

阅读理解。

     Some students think it difficult to learn English well.  That's because they don't find the right way.  I

 think reading is very important for students.  The more you read, the better you'll understand.  Reading is

  helpful to listening, speaking and writing.

     If you often read English aloud, you'll improve your listening.  On the other hand, listening a lot can help

  you to read better.  Reading English everywhere when you are free, if you wish.  You can get a lot of

  knowledge when you read.  Sometimes you need to express your ideas, you can either speak or write.  

 That means you are using what you learned from reading.  The same as Chinese, the more you read, the

 better you can write.  If you want to remember something, you should read again and again.  So from now

  on, you'd better do more reading.  It's a good way to learn English well.

1.  Some students think it difficult to learn English well because _____.

    A.  they don't work hard            

    B.  they are afraid of English.

    C.  they don't find the right way      

    D.  they aren't clever

2.  Reading is helpful to _____.

    A.  speaking      

    B.  listening    

    C.  writing        

    D.  A.  B & C

3.  The writer thinks _____ is a good way to learn English well.

    A.  the better you write            

    B.  doing more reading

    C.  the more you remember          

    D.  the more you write

单项选择题