题目

请高手们给出答案和具体解题思路.
Because of these characteristics of a brown dwarf,it can be easily distinguished from stars in different stages of formation.A brown dwarf is quite distinctive because its surface temperature is relatively cool and because it’s internal composition –approximately 75 percent hydrogen –has remained essentially the same as it was when first formed.A white dwarf,in contrast,has gone through a long period when it burn hydrogen,followed by another long period in which it burns the helium created by the burning of hydrogen surrounding the core.
According to the passage,a white dwarf
A) is approximately 75 percent hydrogen
B) still burns a considerable amount of hydrogen
C) creates hydrogen from helium
D) no longer has a predominantly hydrogen core

提问时间：2021-05-03

答案

首先 ,最明显的 我们可以用排除法直接排除A其次,B的意思我们也可以从文中 has gone through a long perido,by another long period 推翻,与他的still 相矛盾.再者,文中 the helium created by the burning of hydrog...