在操作中不能够删除的图层是（）
A.0图层
B.当前图层
C.含有实体的层
D.外部引用依赖层
参考答案：A, B, C, D
I have learned that it's taking ________ long time to become ________ person I want to be.
A．the; a
B．a; the
C．the; the
D．/; a
The person sitting opposite _____ Mr．Smith is our new manager．
A．to
B．/
C．with
D．of
