为了探究蚂蚁喜欢吃什么样的食物,某生物兴趣小组做了如下实验:
①利用一个较大的玻璃槽器具,放入干湿适当的土壤,上面再覆盖一些蚁穴土壤.
②捕捉20只正常的蚂蚁置于玻璃槽内,在玻璃槽口盖上两层纱布.将上述实验装置放于适宜蚂蚁生活的环境中,进行饥饿处理1~2天.
③取两个大小、形状相同的培养皿,培养皿内分别放入等量碾成粉末状的白糖和食盐,摆放到玻璃槽内.
④3天后,称量培养皿中剩余食物的质量并记录,比较哪种食物减少的最多.
分析实验,请回答:
2014年2月全国人大决定将12月13日作为国家公祭日,与之相关的主要历史事件是( )
下列黏性末端由同一种限制酶切割而成的是( )
彻底摧毁封建专制制度,使“民主”“共和”思想广为传播的资产阶级革命是( )
I was only nine years old when I learnt how to use a computer.My mother is my first teacher.I know how to type,how to copy a file,and how to visit a website on the Internet.One day,mom was not at home.I turned on the computer and began to learn how to chat on net.The first one I met there was a boy called Tom.He greeted me politely.When he knew that I was only a 9-year-old girl and almost knew nothing about chatting on net,he started showing me how to use the chatting tools,how to download,and how to send e-mails.I learnt a lot from him.