He focused the sun's ray on a piece of paper with a burning-glass.

他用一面凸透镜把阳光在纸上聚成焦点。

youdao

He focused the sun's ray on a piece of paper with a burning-glass.

他用一面凸透镜把阳光在纸上集成焦点。

youdao

He focused the sun's ray on a piece of paper with a burning-glass.

他用一面凸透镜把阳光在纸上集成焦点。

youdao