电源是为电路两端提供______的装置，电压是电路中形成______的原因．
电压是电路中产生持续电流的原因；
电源是提供电压的装置．
故答案为：电压；电流．
把下列简单句改为包含定语从句的复合句。
1. Here is the pen. You lost a pen yesterday.
________________________________________
2. The girl told me the news. She is not here now
3. This is a village. My father worked in the village ten years ago.
4. Is this a farm? We visited the farm last year.
5. He is the only one of the students. He knows Frank.
左侧三房心的超声所见，哪一项错误（）
A.左房内有一隔膜
B.左房内隔膜上有孔
C.肺静脉血只回流到真性左房
D.左房内隔膜及合并房缺
E.肺静脉血全部回流到副房
