问答题What does the passage mainly talk about? A. Changing your posture to change your mood. B. Crying when you feel like itD. Being happy if you want to. C. Exercising contributes to health.
问答题动力电池组是由多个蓄电池通过（）方式组合起来电动使用要求。 (2分) A. 串联 B. 并联 C. 交联 D. 互联
