OG详解-OG5 文法 Q28

Choice D is the best answer. The sentence emphasizes the mass of Sirius A, noting that it has a mass of 2.063 solar masses and that it is larger than the Sun.Choice A is incorrect. The sentence makes a generalization about how the mass of stars can be measured; it doesn’t emphasize the mass of Sirius A. Choice B is incorrect. The sentence introduces solar masses as a unit of measurement; it doesn’t emphasize the mass of Sirius A. Choice C is incorrect. The sentence emphasizes the mass of Proxima Centauri, not the mass of Sirius A.