已知非零向量 $\overrightarrow{a}$ 与 $\overrightarrow{b}$ ，那么下列说法正确的是（   ）

    Many teenagers have  ____. But sometimes these can get in the way of ____ schoolwork. Liu Yu is a ____ star on his school team. His dream is to be a  ____ runner when he ____ up. His parents won't allow him ____ so much although they have nothing ____ running. They think their son needs to think about other possible____. Liu Yu ____ with them. He thinks his parents are too strict with him. He also thinks it's very important ____ for himself. Only in this way can he have a chance to achieve his dream.