如图，⊙O与⊙P相交于A，B两点，点P在⊙O上，⊙O的弦BC切⊙P于点B，CP及其延长线交⊙P于D，E两点，过点E作EF⊥CE交CB延长线于点F．若CD=2，CB=2$\sqrt{2}$，则EF的长为(    )

下列设计的实验方案能达到实验目的是（　　）

分数$\frac{8}{9}$的倒数与$\frac{5}{6}$的积是多少?

乌贼遇敌害会释放墨汁，将周围海水染黑，借机逃跑．下列有关的描述不正确的是（    ）

— Nowadays more and more foreigners are becoming interested in Beijing Opera.

—That's true. It's an important part of Chinese____________.