题目内容：

（）theories approximate the truth is the day-to-day business of science.
A.Determinting how closely
B.How closely to determine
C.How one determines close
D.One is close to determining
求A为什么对,BCD为什么错详细解析.
为什么说这里的HOW引导的是感叹句？如果作为提问程度的特殊疑问句讲呢？