通电导线圈周围磁场与电流方向有关，用（）。
A、右手螺旋定则
B、左手螺旋定则
参考答案：A
Have you ever dreamed of staging a concert, ________ thousands of people are applauding and appreciating your music?
A．at which
B．when
C．for which
D．which
选用建筑密封材料时应首先考虑其( )。
A．使用部位和黏结性能
B．耐高低温性能
C．“拉伸-压缩”循环性能
D．耐老化性
