核心价值体系和（）是决定文化性质和方向的最深层次要素，是一个国家的重要稳定器。
参考答案：核心价值观
如果一个比例两个外项的积是最小的质数，其中一个内项是0.5，另一个内项是（ ）。
I ____ to reach the manager for the last two hours but the line is always busy. [ ]
A. tired
B. have tired
C. had tired
D. have been trying
