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Focal point is, the distance between the two is the focus of the focal length.
定点是焦点，两焦点的距离是焦距。
youdao
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The principle of solar energy: focus on a focal point to produce heat.
⊙、太阳能的原理：集中在一个焦点上才能产生热。
youdao
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The principle of solar energy: focus on a focal point to produce heat.
⊙、太阳能的原理：集中在一个焦点上才能产生热。
youdao