【简答题】阅读理解 Experts say that agriculture provides four percent of the world's greenhouse gas emissions each year. The gases released include carbon dioxide, a major cause of global warming. Twenty-one na...
【单选题】Which of the following refers to the retention of the Sun's warmth in the Earth's lower atmosphere by greenhouse gases?
【判断题】投加助凝剂的作用是减弱混凝效果。生成粗大结实易于沉降的絮凝体。
【单选题】What will be the result of the greenhouse effect?
A.
The earth's temperature will change irregularly.
B.
The amount of carbon dioxide will be reduced.
C.
The global temperature will gradually increase.
D.
Much more sunlight will be blocked by CO2.
【判断题】投加助凝剂的作用是减弱混凝效果,生成粗大、易于沉降的絮凝体。
【单选题】1mol理想气体在T1=400K 的高温热源与T2=300K 的低温热源间作卡诺循环,在T1=400K 的等温线上起始体积为V1=0.001 ,终止体积为V2=0.005 ,则此气体在每一循环中 对外所作的净功是
【单选题】The United States is the world's No. 1 emitter of greenhouse gases.
【简答题】1 mol 理想气体在 T 1 = 400 K 的高温热源与 T 2 = 300 K 的低温热源间作卡诺循环(可逆的),在 400 K 的等温线上起始体积为 V 1 = 0.001 m 3 ,终止体积为 V 2 = 0.005 m 3 ,则此循环的效率为 %
【单选题】1 mol 理想气体在 T 1 = 500 K 的高温热源与 T 2 = 400 K 的低温热源间作卡诺循环.在 500 K 的等温线上起始体积为 V 1 = 2 l ,终止体积为 V 1 = 10 l ,则此气体在每一循环中所做的净功 A 为
【单选题】以下几种设备用于星型网络连接,位于网络的中心的是( )。