习题7-1
地质图上表现为中间老、两侧变新的对称分布地层，这种构造通常是：（）
The geological map shows a symmetrically distributed stratum in the middle and new on both sides. This structure is usually: ()

A．向斜 | syncline
B．背斜 | anticline
C．正断层 | Normal fault
D．逆断层 | Reverse fault