The dictionary is ______: many words have been added to the language since it was published.
A:out of control
B:out of date
C:out of sight
D:out of reach
①曲线 C1 的焦点为“差型点”;
②曲线 C1 与 C2 有公共点;
③直线 y=kx 与曲线 C2 有公共点,则 |k|>1 ;
④原点不是“差型点”.
其中正确结论的个数是____.