Reversals

例句:

• Proper reversals of the current are accompanied by continuous motion, and since the disk and shaft rotate with the coil, there is continuous rotation. 伯莎M.克拉克. 科学通论.
• When such reversals do not take place, the currents are said to be direct. 佚名. 神奇的知识之书.

校对:诺艾尔