一个空瓶质量是200 g，装满水总质量是700g，现先向瓶内装一些金属颗粒，使瓶和金属颗粒总质量为1kg，然后再向瓶内装满水，则三者质量为1410g。则该金属可能是（  ）（ρ_铁=7.8×10³kg/m³；ρ_铜=8.9×10³kg/m³；ρ_铝=2.7×10³kg/m³）

完形填空

     There is a saying, “No sports, no life.” Sports are very important to us. Sports help us to stay  1  and get good grades. Everyone in our class   2  sports. Our favourite  3  is PE. We only have PE lessons  4  a week, but we play sports every day. The most popular sport in our class is basketball. The boys enjoy  5  it, and many of the  6  like it, too. Another popular sport is football and there   7  a lot of football fans (球迷) in ourclass. When the weather is 8 , we often play ping-pong outside.We hardly ever (几乎不) play volleyball. We think it's  9. We have a basketball team. Our team often has friendship (友谊) matches (比赛) with teams from other schools. When there is a match, many of us go to  10  it. It's very interesting.

下列关于生物技术的安全性和伦理问题的叙述正确的是

独自莫凭栏，无限江山，____。____，____。（李煜《虞美人》）