分别用电动势表示电源和用端电压表示电源的电路图正确的是(____)。
A图<img src="/tupian/shandong/jining/dgjc01.png"/>
B图<img src="/tupian/shandong/jining/dgjc02.png"/>
C图<img src="/tupian/shandong/jining/dgjc03.png"/>
D图<img src="/tupian/shandong/jining/dgjc04.png"/>