A:π12
B:π6
C:π4
D:π3
做测定“小灯泡的电功率”实验时,所用器材有:电压为3V的电源,额定电压为2.5V的小灯泡,以及符合实验要求的滑动变阻器、已调零的电流表和电压表、开关、导线若干.
—Although my son failed the exam, he tried his best to________
— He is old enough to control his feelings.
一个三角形的高是6.5米,面积是56.55平方米,底是____米