2-2×15-15
=2-25-15
=75(千克)
故答案为:75.
Nov. 26th is Monday. Nov. 14th is ______________.[ ]
A. Wednesday
B. Thursday
C. Saturday
关于X线管的阳极特性,错误的是()
A.灯丝加热为定值时,管电压增加,管电流增加
B.管电压增高,空间电荷减少,管电流减小
C.管电压相同,灯丝电流增加,管电流增加
D.管电压相同,灯丝电流增加,管电流减小
E.管电流相同,管电压高的灯丝加热电流低