题目

如图所示，等臂杠杆AB两端各挂体积相同、质量相等的铁球和铜球(杠杆和挂线均是电的良导体)，在水平位置平衡，同时将铜球和铁球分别浸没在盛有CuSO4溶液的水槽中。过一段时间后会发现（    ） A.杠杆A端下倾                     B.杠杆B端下倾 C.杠杆先A端下倾，后B端下倾       D.杠杆仍在水平位置平衡Old age may not sound【1】_______ (excite).But recent findings provide good news for older people and for people 【2】_______ (worry) about getting older.The findings came from 【3】______ survey of more than 340,000 adults in the United States. The Gallup Organization questioned 【4】______ by telephone in 2008.At that time, the people were between the ages of eighteen and eighty-five.The researchers asked questions about emotions like happiness, 【5】________(sad) and worry. They also asked about mental or emotional stress. The research team found that levels of stress were 【6】________ (high) among adults between the ages of twenty-two and twenty-five. Stress levels dropped【7】_______ (sharp) after people reached their fifties.Happiness【8】_______ highest among the youngest adults and those【9】_______ their early seventies. The study also showed that men and women have similar emotional patterns as they grow older. 【10】______ , woman at all ages reported more sadness, stress and worry than men.