坚持社会主义的性质最根本的是必须坚持
A.以经济建设为中心
B.四项基本原则
C.公有制的主体地位不动摇
D.马克思主义
参考答案:C
He served in the army in _______ when he was in his twenties. [ ]
A. 1940's
B. 1940s
C. the 1940s
D. the 1940s'
请用不超过200字的篇幅,概括出给定资料所反映的主要问题。要求:全面,有条理,有层次。