1839年8月19日法国人()向世界公布了摄影术。.
参考答案:雅克.曼岱.达尔盖
如图所示,电源电压保持不变,当滑动变阻器的滑片P向右移动时,电流表和电压表的示数变化情况是( )
A.电压表的示数变大,电流表的示数变小
B.电压表的示数变大,电流表的示数变大
C.电压表的示数减小,电流表的示数增大
D.电压表的示数减小,电流表的示数减小
The doctor asked the man what _____. [ ]
A. the matter was
B. was the wrong
C. was the matter
D. was his trouble