为什么到临界转速附近时,轴承振动会明显增大?
参考答案:
由于转子质量不平衡产生的扰动力的频率与转子的固有频率重合而产生共振.
短文填空 根据短文内容及首字母提示补全单词。
Reading is a very important skill for us students. Different people have different 1)r________ habits. Every student should have a good reading habit. Now let me tell you 2)a________ my reading habit. I spend most of my 3)s________ time on reading. It takes me 4)o________ ten hours to read different types of books. On weekends, I usually read for about half an hour before I go to bed. But I read a 5)l________ more at the weekends than on the weekdays. My favourite kind of book is science. At the same time, I read a lot of books about 6)c________ in different countries. Then I can learn more about these countries.
I get these books from other students or the school library. I 7)s________ buy books. But I often read some books in the bookshop. In the school library, I often read with my classmates and friends. After reading, we can chat with each other and 8)d________ what to learn from the books. We can also take the books out and keep them for a week. After I finish reading them, I will 9)r________ them to the library.
I think reading can make me happy. The good books 10)h________ been my friends. They are the key to the success. So let’s enjoy reading and get a lot from books.
窗体上画一个名称为Command1的命令按钮,然后编写如下程序: Optlon Base 1 Prlvete Sub Command1_Click() Dim s As Variant a=Array(1, 2, 3, 4, 5) Sum=0 For i=1 To 5Sum=Sum_a(i) Next i X=Sum/5 For i=1 To 5If a(i)>x Then Print a(i); Next i End Sub 程序运行后,单击命令按钮,在窗体上显示的内容是______。
A.1 2
B.1 2 3
C.3 4 5
D.4 5