1.According to the passage, the sixth sense in dogs is ________.
B. generally assumed supernatural
2.It's the detection of subtle differences and changes in the earth's magnetic field that ________.
A. gives dogs a good sense of direction
3.Dogs may become intensely alarmed and begin trembling when ________.
C. a storm is going to happen
4.What helps a dog know whether a buried person is alive or not?
D. The infrared heat sensors on the dog's snout
5.Which of the following statements the author would probably agree with?
C. Dogs have more kinds of perceptions than people because they need them.