A:why
B:how
C:unle
D:where
理想变压器正常工作时,原线圈一侧与副线圈一侧保持不变的物理量是( )
As I joined the big crowd, I got________from my friends.
质量为0.2千克的水温升高50℃,求水吸收的热量Q吸.C水=4.2×103J/(kg•℃).