题目选项分析

Physicists, using extremely sophisticated instruments, have documented that the component particles of atoms—protons, neutrons, and electrons—comprise many smaller units called hadrons that are themselves composed of quarks, particles whose radii are 2,000 times smaller than a proton.

Physicists, using extremely sophisticated instruments, have documented that the component particles of atoms—protons, neutrons, and electrons—comprise many smaller units called hadrons that are themselves composed of quarks, particles whose radii are 2,000 times smaller than a proton.