地球本身是一个大磁体,地球周围存在磁场。地磁场北极(N极)位于地理的___________附近,小磁针由于受到地磁场的作用,静止时N极指向地理的___________。
南极,北极
We'll climb the hill if it tomorrow. [ ]
A. won't rain
B. isn't raining
C. doesn't rain
桥式起重机操作的基本要求?