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问题 选择题
如图所示，处在磁感应强度为B的匀强磁场中的单匝矩线圈abcd，以恒定的角速度ω绕ab边转动，磁场方向垂直于纸面向里，线圈所围面积为S，线圈导线的总电阻为R．t=0时刻线圈平面与纸面重合，且cd边正在离开纸面向外运动．则正确的是（　　）

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

答案

答案：C

改错题

改错

1. To she surprise, this phone call changed her life.          (      )

          A        B                                 C       D

2. Parents should not be too strict in teenagers.                (      )

       A                        B  C           D

3. I can't think of any good advices to give her.                ( )

                   A      B                C                 D

4. I haven't seen my cat for two days. I'm very worry about her.           ( )

                 A                  B                                  C               D

                                                                                                             ( )

5. You would rather stay at home and read a book than to go to a party.

                  A                   B                                      C             D

                                                                                                                            ( )

                                   
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单项选择题 案例分析题

我国某校地理小组，根据当地楼房各朝向外墙面接受太阳辐射热量的实测值，计算出一月和七月的太阳辐射热日总量变化方位图。据此完成第下列题。

为充分利用太阳能，该地房屋主墙面应朝向（）

A.南方

B.北方

C.东南方

D.西南方
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