登封“天地之中”历史建筑群与（）同时入选《世界遗产名录》。
A.福建武夷山
B.中国丹霞
C.中国南方喀斯特
参考答案：B
While other scientists are keeping____eye on changes in the H5N1 bird flu strain, the scientists in England are working on vaccines, in case it becomes highly infectious in ____humans.
A．a , /
B．an, /
C．the, an
D．an, the
菊花的药用部位是
A．干燥花B．花蕾C．花序D．花粉E．柱头
