如图15-3-9所示，匀强磁场中有一通以方向如图的稳恒电流的矩形线圈abcd，可绕其中心轴OO′转动，则在转动过程中( ) 图15-3-9 A.ad和bc两边始终无磁
用括号内所给单词的适当形式填空。 1.These are Jim and Tim. _____________________________ (It) are brothers. 2.Are __________________________ (that) your brothers? 3.Two _____________
设数列{an}的前n项和为Sn,已知2Sn=3an+3,则Sn= .
下列说法中，不反映我国社会主义民主政治特点和优势的是 A．我国民主的内容与形式相统一 B．民主是全民的，具有广泛性和真实性 C．在我国，
在学校“运用物理技术破案”趣味游戏活动中，小明根据“通常情况下，人站立时身高大约是脚长的7倍”这一常识，可知留下图中脚印的“犯罪嫌疑人
—Have you ever been to Hong Kong？—Yes, I ＿＿＿ there last month.A. went to B. have been C. went
Real policemen hardly recognize any resemblance between their lives and what they see on TV.The first difference is that a policeman’s real life revolved round criminal law. He has to know exactly w
An boy worked out the English problem. A. 8 years old B. 8 years C. 8 year old D. 8-year-old
为虚数单位，且
，则
的值为
C．
D． 
