(back and forth)这个英文是什么意思?
问题描述：
(back and forth)这个英文是什么意思?
答
back and forth反复地,来回地往返前前后后来来去去同义词to and from例句：A stepper motor,which can be turned a degree at a time,would twist the wand back and forth as needed.至于一次可以转一度的步进马达,...