油气聚集
参考答案：
油气在运移过程中，遇到圈闭形成油气藏的过程。
Ms Black is considered a________lady by her neighbors, for she often helps the poor old man next door. [ ]
A. generous
B. hopeful
C. mean
D. selfish
如图中能够反映出北京文化职能的是（ ）
A．①②③④
B．①②③
C．②③④
D．①③④
