在我们的生活中，3G手机通信业务已经非常普遍，使用3G手机不仅可以通话，还可以随时通过无线网络上网．下列说法正确的是（  ）​

$\frac{1}{2}$ 公顷的 $\frac{3}{4}$ 是____公顷，合____平方米。

①表明我国综合国力日益增强                                    ②彰显我国负责任的大国形象 
③表明我国是发展最快变化最大的发达国家之一    ④能够增强中华民族的自信心和自豪感

从人种的角度来说，中国人属于（　　）

    Jack and Anna are good friends. They are Chinese. Jack likes sports very much. He can play volleyball , basketball and football . Anna likes music very much . She can't play ball games. But they both like playing on computers . They like eggs , bread and milk for breakfast . For lunch , Anna likes eating vegetables and fruit , but Jack likes chicken and fish . They both like hamburgers .But they don't like ice cream or rice.