民以食为天，食以安为先，面对层出不穷的食品问题，玲玲所在班级准 备就食品安全问题开展主题班会。玲玲和同学们整理了相关材料，

材料一：在今年的十二届人大二次会议上，“舌尖上的安全”首入政府工作报告。***说：“用最严格的监管、最严厉的处罚、最严肃的问责，坚决治理餐桌上的污染，切实保障舌尖上的安全。”
材料二：2014年3·15晚会的主题是“让消费更有尊严”。晚会曝光力度空前，如尼康D600被曝拍照现黑点；澳妙可奶粉篡改保质期；大唐电信旗下公司为手机装恶意软件；广琪贸易公司售过期食品原料等。

请你参与其中并结合所学知识，回答下列问题：

    Many people like spring, because they can go out and do many kinds of activities. We made a survey about the activities that people like to do in spring. Here are the results.
Scott：
    In spring, I often visit my uncle and I like fishing with him. I also like boating and enjoy the beach. Last spring my uncle and I went boating. The dolphins came so close to us. It was very amazing. I hope that I can go there again soon.
Linda:
    My favorite spring activity is gardening (园艺). I think it is relaxing to work in the garden. I grow many flowers in my garden every year. They are so beautiful.
Nancy：
    I love spring. I love going to the beach and spending a whole day there. It is so relaxing to lie on the beach. I also like surfing in the sea.
James：
    I am twelve years old. My favorite spring activity is swimming. I started to learn swimming when I was seven years old. I always have a good time with my friends in the river.

　　　 was to blame．

现有1000个氨基酸，其中氨基有1020个，羧基有1050个。则由此合成的含有4条链的多肽中共有肽键、氨基、羧基的数目分别是（  ）

投资商在某城市内进行大型购物中心区位选择时，可利用该城市的GIS系统作综合分析，其调取的主要参考图层是（  ）