题目

GPS has completely transformed how we get around. But other animals have long had their navigation (领航) systems built right in.“We know their eyes are quite sensitive to polarized (偏振的) light and the sky has a particular pattern of polarized light relative to the position of the sun,” Barbara Webb, a researcher at the University of Edinburgh, says.You can see polarized light firsthand if you take a pair of polarized sunglasses and spin them against the sky-the light passing through the glasses changes. Webb says the insects have polarization like that built into their many eyes. 5．金属材料在生活、生产中应用十分广泛．（1）（1）下列有关金属的成语中，发生化学变化的有DA．沙里淘金B．斩钉截铁 C．铁杵成针 D．百炼成钢（2）2010年1月，上海世博会贵金属特许商品正式发布．如图标出了第一组纪念金条的规格、成色等指标．品种成色重量规格最大发行量上海世界博览会彩色纪念金条第一组99.99%500g100×45mm100条100g72×32.4mm3500条50g60×27mm6000条20g48×21.6mm15000条该纪念金条是混合物（选填纯净物或混合物）．俗语常言“真金不怕火炼”，这是因为金具有热稳定性强的化学性质．