This is a photo of me. I was in Qinhuangdao. I swam in the sea. It was sunny. The sky was blue. I watched many ships on the sea. I liked to swim. I had fun.
人体血液循环系统由____、____ 、____ 组成。
- Don't talk in class, please.
- Sorry, I__________.
关于电流表和电压表的使用方法的比较，下列说法错误的是( )
