沉积纹层一个大层了里面所包含的小层数是（）。
A、2个
B、3个
C、4个
D、5个
参考答案：D
— Look! You’ve made the same mistake again!
— Oh, not again! _________ such a mistake.
A．I will always make
B．I’m always making
C．I’ve always made
D．I always made
外部实体
