在如图所示的圆锥摆中，已知绳子长度为L，绳子转动过程中与竖直方向的夹角为θ，试求小球做圆周运动的周期____．

    Breakfast is very important. It is one of the most important1of the day. To keep healthy, everyone should2a good breakfast.3the right food is necessary for good health. We may have eggs, bread, milk and so on,4breakfast. Many students go to school without breakfast5they get up late or their parents don't cook for them. It's6for their health.7breakfast children may not grow fast and may not study and play very well at school. They may8. And when they're ill, they will9a long time in recovering (恢复). I think everyone should have some good10habits. It is necessary.