当前位置:首页 > 学历类

[单项选择]

Passage Three All the useful energy at the surface of the earth comes from the activity of the sun. The sun heats and feeds mankind. Each year it provides men with two hundred million tons of grain and nearly ten million tons of wood. Coal, oil, natural gas, and all other fuels are stored-up energy from the sun. Some was collect ed by this season’s plants as carbon compounds. Some was stored by plants and trees ages ago. Even waterpower derives from the sun. Water turned into vapor by the sun falls as rain. It courses down the mountains and is converted to electric power. Light transmits only the energy that comes from the sun’ s outer layers, and much of this energy that is directed toward the earth never arrives. About nine-tenths of it is absorbed by the atmosphere of the earth. In fact; the earth itself gets only one half-billionth of the sun’ s entire output of radiant energy.

For mankind, the sun is the source of ()
A. solar activity
B. all heat
C. all food
D. both B and C

参考答案:

您可能感兴趣的题目:

政府预算执行的支出机构主要是
主张根据儿童的兴趣和需要去设计教育活动的教育家是( )
在DBMS中,提供从逻辑到物理存取结构桥梁的子系统是( )
证券投资基金由( )发起设立。
腹腔镜检查可能出现:
本病例应诊断为
Not until I shouted at the top of my voice______th
某企业向两个保险公司投保了企业财产保险综合险,属于重复保险,保险金额分别为1000万元和2000万元
输血不是作为主要传播途径的病毒性疾病为()。
用C语言编写的代码程序( )。
在线 客服