7. Where does Fred meet Ann? A. At Brown’s house. B. In the hospital. C. At the station. D. At Kay’s house. 8. How many hours a week does Fred do his part—time job? A. Five h
Everyone wants to be self-confident, but maybe we just don’t know how to be. Here are some tips on how you can feel more confident about yourself. 71 Everyone has shortcomings. When you have
满足什么条件时，
：
，
：
，
：
三条直线只有两个交点？
时，三条直线有两个交点
时，
的方程均为
，即三条直线重合；
，
，
，
且
与
都和
相交．