所谓_________，是指构成各门学科的基本事实及其相应的基本概念、原理和公式及系统。
参考答案：基础知识
9+6（a+b）+（a+b）2
—Did you see the film last night?
—Yes, I have never seen _______ exciting film before. [ ]
A. such a
B. so an
C. such an
D. so an
