A:电流表A的示数减小
B:电压表V的示数变大
C:电压表V示数与电流表A1示数的比值不变
D:电流表A1的示数不变
11-9=____
8+5=____
16-9=____
13-7=____
When you see an English film or talk with native speakers, observe their facial expressions and g____.