①我国国民受教育年限和发达国家相比有很大的差距

②我国人口基数大，人口增长快

③我国的人口分布不平衡

④与发达国家相比，我国的人口素质偏低

（1）计算：$\sqrt{9}$+2cos60°+${\left(\frac{1}{2}\right)}^{-1}$-${2011}^0$

（2）化简$\frac{a^2-1}{a}÷\left(a-\frac{2a-1}{a}\right)$．

下列关于动物的生活环境及获取食物的方式的叙述中，不正确的是（　　）

    Sally is 76 years old. She has no sons 1 daughters. Her husband（丈夫） died(死) 15 years 2. But she didn't move into an old people's home. She would like to look after(照顾) herself . Every morning she gets up early and goes for a walk in the park. She likes doing sports in the park, too .When she does these things, She feels very 3.

    Every day she spends two hours 4 children with their math. And she was a popular 5 before she retired(退休) from a middle school. When the children come 6 help, she is always happy to help them. She often says to the children,“I'm so 7 to be with you. You are all my kids. ”

    When people ask her 8, she says,“I love children and 9 staying with them. Every kid is a 10 for me. ”