法律体系的基础是( )。
A．宪法
B．民法
C．行政法
D．劳动与社会保障法
参考答案：A
Teachers have to constantly update their knowledge in order to maintain their professional________.[ ]
A. consequence
B. independence
C. competence
D. intelligence
干燥剂的组成与煤种及制粉系统热平衡有何关系？
