图上1厘米代表实地距离300千米的比例尺，正确的表达是[ ] A．1：3000

运载三名航天员并实现太空行走的“神舟”七号飞船在太空飞行过程中，航天员在飞船内可以直接对话，但在飞船外共同作业时，他们不能直接对话，必须借助电子通信设备进行交流，原因是    [ ]

A．太空中噪声太大        

B．宇航服不能传递声音    

C．声音能在真空中传播    

D．声音不能在真空中传播

2013年2月23日，湘、鄂、赣、皖四省会城市“掌门人”聚首武汉，共同签署《长江中游城市群长沙、合肥、南昌、武汉战略合作框架协议》。长江中游城市群即“中三角”，包括武汉城市圈、长株潭城市群、鄱阳湖经济圈、江淮城市群等中部经济发展地区，共同打造国家规划重点地区和全国区域发展新的增长极。上述协议的签署，意味着四省各方既有合作也有竞争。下面正确表述合作与竞争关系的是

A．合作与竞争彼此不分

B．合作与竞争相互依存

C．合作与竞争水火不容

D．合作与竞争各显神通

建筑施工的各种安全设施、防护装置如有损坏的，必须及时整改，确保使用安全的可靠性。安全设施的拆除必须经( )确认其已完成防护作用并批准后，方可拆除。

A．项目经

B．安全设施设计人

C．项目工程技术负责人

D．作业队施工负责人

按规定，我国中央级金融租赁公司由( )监管。

A．中国人民银行

B．中 * * 银行

C．中国政策性银行

D．中国人民银行省级分行

About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along free on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.
The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots withorganic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.

Roots have the ability to ______.

A．make proteins

B．obtain fresh air

C．produce inorganic nitrogen

D．carry out activities without energy