【单选题】与外加电场相比,各向同性均匀电介质中的电场
A.
较大,因为极化电荷产生的场强与外加电场方向相同
B.
较小,因为极化电荷产生的场强与外加电场方向相反
C.
不变,因为各向同性电介质中电荷密度为零,不产生附加电场
【简答题】英语(基础模块)第一册(修订版)期末试题 I. 词汇与语法 ( ) 1. They don ’ t have a lot of time ________ with me. A. talk B. to talk C. talking ( ) 2. ______ important to make some friends. A. This is B. That is C. It is ( )...
【单选题】与外加电场相比,各向同性均匀电介质中的电场
A.
不变,因为各向同性电介质中电荷密度为零,不产生附加场强
B.
较小,因为极化电荷产生的场强与外加场强方向相反
D.
较大,因为极化电荷产生的场强与外加场强方向相同
【单选题】与外加电场相比,各向同性均匀电介质中的电场
A.
较大,因为极化电荷产生的场强与外加场强方向相同。
B.
较小,因为极化电荷产生的场强与外加场强方向相反。
C.
不变,因为各向同性电介质中电荷密度为零,不产生附加场强。
【单选题】According to the first paragraph, which of the following statements is not true?
A.
Railroads provided relatively easy access to the west for the first time.
B.
Railroads performed a useful service in extending the frontier and helping to achieve national unity.
C.
There were abuses about building and operating the railroads.
D.
The economy of the west is robust.
【单选题】Which one is equivalent to“railroad crossing”?