Millions of people watched that first moon landing on television, their hearts in their mouths, aware of how difficult and dangerous an adventure it was, and what risks had to be ____.

A．taken

B．take

C．to take

D．taking

下图为某地某水平面的岩层分布图，读图回答下面1-3 题。

1 、图中丁的地质构造为 [     ]

A．褶皱      

B．背斜    

C．向斜      

D．断层

2、关于图示的叙述正确的是     [     ]

A．甲为良好的储油构造

B．甲有利于储存地下水

C．修一南北向隧道应选址丁处

D．图中岩层为岩浆岩

3 、若该地地表甲为谷地，丁为山岭，其成因是[     ]

A．地壳运动所致        

B．内力作用所致    

C．岩浆活动所致        

D．外力作用所致