凸透镜近轴光线中，入射线和与其对应且相平行的出射线构成共轭光线，其入射点跟出射点的连线与主光轴的交点，称为凸透镜的焦点，位于透镜中央的点叫光心。
如果老师是星光，我就是星光心中的明星。
If the teacher is a star, I am the star light in the heart of the star.
冠心病；外科治疗；激光心肌血运重建术。
Coronary heart disease; Bypass surgery; Transmyocardial laser revascularization.
乐观的秘密并不偶然——高度乐观的人需要努力来维持他们的阳光心态。
The secret to optimism is that it doesn't just happen — highly optimistic people have to work on maintaining their sunny attitudes.
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