已塑化的乙酸纤维素粉
参考答案:39121200
若i1=10sin(314t+90°),i2=10sin(314t-90°),i3=10sin314t,其单位是A,当它们通过同一电阻,且通电时间相等时,发热量最大的是()。
A.i1
B.i2
C.i3
D.三者相等
When should a fire be ventilated?()
A.When attacking the fire directly
B.When using a steam smothering system
C.When using the fixed CO2 system
D.All of the above