国家元首
参考答案：是国家机构的组成部分，是国家对外对内的最高代表。
Jay is one of _____ in China. [ ]
A. a popular singer
B. more popular singers
C. the most popular singer
D. the most popular singers
防烟排烟系统中排烟口距可燃物或可燃构件的距离不应小于（）m。
A.1
B.1.5
C.2
D.2.5
