The main idea of this passage is to______.
A. introduce the institutions in higher education
B. evaluate the institutions in higher education
C. clarify the institution terms in higher education
D. classify the institutions in higher education
身份与烟叶外观质量和内在化学成分有密切关系,一般来讲,()。
A. 身份薄的烟叶颜色深,氮类化合物含量高
B. 身份中等的烟叶颜色深,氮类化合物含量高,质量好
C. 身份厚的烟叶颜色深,氮类化合物含量高
D. 身份厚的烟叶颜色深,氮类化合物含量低