A:使线圈匝数增加一倍
B:使磁感应强度的变化率增大一倍
C:使线圈横截面积增加一倍
D:使线圈匝数减少一半
组词。
包____ 钟____ 元____
跑____ 种____ 无____
It's impolite ____ with chopsticks .
—Will you please give some advice on _________ English at home?
—Well, do a lot of reading and listen to English programs.
关于物体的内能,下列说法正确的是( )