标准煤的发热量为()。
A.20934kJ
B.25120.8kJ
C.29302kJ
D.12560.4kJ
参考答案:C
—Mum, can I go skating now?
—Well, you may go after your homework _____. [ ]
A. has finished
B. will finish
C. is finished
D. was finished
根据磁感应强度的定义式,下列说法中正确的是( )
A.在磁场中某确定位置,B与F成正比,与I、L的乘积成反比
B.一小段通电直导线在空间某处所受磁场力F=0,那么该处的B一定为零
C.一小段通电直导线放在B为零的位置,那么它受到磁场力F也一定为零
D.磁场中某处的B的方向跟电流在该处所受磁场力F的方向相同