在鸟的受精卵里，将来发育成雏鸟的部位时（　　）

    1children like to watch TV. It' s very 2. On TV3can see and learn a lot and know many things 4 their country and the world.5they can learn over the radio. But they can learn better and more easily on6.Why? Because they can hear and watch at the same time. But they can' t 7 anything over the radio.

    Many children watch TV only on Saturday or Sunday evening.They are 8 busy with their lessons. But a few children watch TV every 9. They go to bed very late. They can' t have a good10. How about you, my young friend?

已知向量$\overrightarrow{a}=\left(m,n\right),\overrightarrow{b}=\left(1,2\right),\overrightarrow{c}=\left(k,t\right)$，且$\overrightarrow{a}\parallel \overrightarrow{b},\overrightarrow{b}\perp \overrightarrow{c},\left|\overrightarrow{a}+\overrightarrow{c}\right|=\sqrt{10}$，则mt的取值范围是（    ）

小强今年8岁，他和爸爸、妈妈住在一起，一家三口幸福快乐。小强家的家庭结构属于（    ）