下列不属于目前人类面临的主要人口问题的是（　　）

下列有关我国自然资源的叙述，正确的是（    ）。   

C

    Hello! My name is Jack.I am from England.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，some bread and porridge(粥) for breakfast.I don't like milk.I have no time to go home for lunch，so I have it at school.The lunch at school is very good.I often have noodles and dumplings.Noodles are my favourite food. Sometimes I have different foods for lunch.I eat rice，meat and vegetables.I always go home early in the afternoon.Then I do my homework.I have supper with my parents.Sometimes we go out to have dinner with our friends.We are happy in China.

金属材料的性质在很大程度上决定了它们的用途。下列说法中不正确的是（　　）