Hello! My name is Mike. I am from the USA. Now I am in China with my parents. I like China. I like Chinese food, too. I have breakfast at home. I eat an egg, bread and porridge(粥)for breakfast. I do not like milk. I have no time to go home for lunch. So I have it at school. The lunch in our school is good. I can have different food for lunch. I eat rice, meat and vegetables. Sometimes I have noodles（面条） and dumplings(饺子). I have dinner at home with my parents. Sometimes we go out to eat with friends. We have chicken, vegetables and fruit.

$m=\sqrt{a}+\sqrt{a+5},n=\sqrt{a+2}+\sqrt{a+3}\left(a>0\right)$，则有(    )

秦国发展成为战国后期最富强的封建国家,主要是因为  (    )

I can d____.

耳是重要的听觉器官，它包括____ 、____ 和____ 三部分。中耳是传导声波的通道，由____ 、____ 和____ 组成。