In Beijing, the weather is ___________ in July.[ ]
A. sun
B. snowy
C. sunny
答案:C
A.时刻t线圈中电流的瞬时值icosωt
B.线圈中电流的有效值I
C.线圈中电流的有效值I=
D.线圈消耗的电功率P
直立褶皱(erect fold)