请结合下图,回答问题。
(1)图中呈现了我国的哪些人口问题?
________________________________________________________________________________________________________________________________________________________________________________________
(2)上述人口问题对我国发展带来了哪些不利影响?
________________________________________________________________________________________________________________________________________________________________________________________
(3)结合所学的知识分析图中两条曲线形成的原因?
________________________________________________________________________________________________________________________________________________________________________________________