定义在R上的函数$f\left(x\right)$满足$f\left(4\right)=1$．$f\text{'}\left(x\right)$为$f\left(x\right)$的导函数，已知函数$y=f\text{'}\left(x\right)$的图象如图所示．若两正数$a,b$满足$f\left(2a+b\right)<1$，则$\frac{b+2}{a+2}$的取值范围是（　　）

Should teenagers be asked to move out when they start working? People in different countries have different ____.

In many Western countries, teenagers are allowed to move out at the age of____. Their parents believe that they should be____ to care for themselves from an early age. In this way, when they start working, they can  ____

their own lives. In most Asian societies,____,it is not common for teenagers to move out. Chinese parents believe that ____  is better for children to live with parents who can take care of them. But the young should then look after their parents when they get____. That is why many Chinese adults continue to live with their parents, even ____ they get married.

设随机变量X：B（6，$\frac{1}{3}$），则D（X）等于（　　）