电流的大小和方向都不随时间的变化而变化，则称其（）
参考答案：直流
根据句意和所给中文写出句中所缺的单词。
1. If you have a _____ (机会) to go, take it.
2. Do you know the saying, "Practice makes _____ (完美的)."
3. She went to Beijing with the _____ (目的) of learning from the teachers
there.
4. He is here in body, but not in _____ (精神).
5. Shall I _____ (记录) what he says?
电导天线发射电磁波的工作原理，与光整流发射有何不同？
, "Practice makes _____ (完美的)."
.