物质由分子构成，而分子由原子构成。

Matters consist of molecules, and molecules of atoms.

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所有的物质都是由分子构成的，而所有的分子内都有微小的原子、带正电荷的质子、中性的中子和带负电荷的电子。

All materials are made up of molecules, and all molecules have tiny atoms, with positively charged protons, neutral neutrons, and negatively charged electrons.

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激光在生物学和医学中应用的主要机理是激光的能量必须转化为其他形式，构成生物组织的分子和原子能够吸收激光的能量，而最终把它转化成其他能量形式。

The main mechanism of the application of laser in biology and medicine is that the molecule and atom of the tissue can absorb the energy of laser and ultimately transform it into other forms.

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