题目

The first time I went hunting wild geese with my father, I couldn't catch them no matter how hard I tried. Every time I tried to approach them, _______ the wild geese started flying away before I could get close. It _______ me a lot and I turned to my father for help.Hearing my trouble, my father _______ at a wild goose standing at the highest point and said, “That wild goose is a sentry （哨兵）,which we call the wild goose _______ . It will give an alarm to the other wild geese as long as it finds something _______ .“That's _________it is so hard for you to catch them. Listen, boy! G如图所示所在通电螺丝管内部中间的小磁针，静止时N极指向右端，则电源的c端为正正极（填“正”或“负”），螺线管的a端为SS极（填“N”或“S”）