电流的磁效应
参考答案:
电流在其周围的空间产生磁场,当载流导体处于该磁场中时,将受到力的作用,这种效应称为电流的磁效应。如电动机、电磁测量仪表等都利用了这一原理。
阅读理解。
Tom is a student of a primary school. He has only four lessons every day but he goes to school six
days a week. The following is his school timetable.
Timetable
1. Tom is a .
A. middle school student
B. senior school student
C. primary school student
2. How many subjects does Tom have at the school?
A. Five
B. Six
C. Seven
3. Tom doesn't go to school on _ .
A. Tuesday
B. Sunday
C. Saturday
4. How many lessons does Tom have a week?
A. Twenty
C. Twenty-four
5. Which subject doesn't Tom have at school?
A. Spanish
B. Chinese
C. English
流感病毒的血凝素和神经氨酸酶属于()
A.衣壳
B.核心
C.包膜
D.刺突
E.壳粒