在同一平面内放置六根通电导线，通以相等的电流，方向如图所示，则在a、b、c、d四个面积相等的正方形区域中，磁场最强且磁感线指向纸外的区域是(    )

如图，已知直线AB、CD相交于点O，OA平分∠EOC，∠EOC=110°，则∠BOD的度数是（　　）

根据短文内容，判断下列各句正误。
      Hong Kong has about forty public beaches. Some of them are very famous around the world. People can go there for a swim. You can go to them by bus. To go to some beaches you must take a boat.
    You will swim there without danger if you remember these instructions:
    Never swim alone.
    Never go out in a boat if you cannot swim.
    Never swim after a meal or when you feel hungry or tired.
    Don't stay in the water too long.
    Remember: A red flag means that it is dangerous for anybody to go into the water. A blue flag means that it is dangerous for children.