Environmental health scientist Dickson Despommier and his students came up with the idea of a “vertical(垂直的) farm”. A vertical farm is a glasswalled structure that could be built as tall as a skyscraper(摩天大楼). Since the garden is built upwards, rather than o...
A tree that is 10 feet tall casts a shadow on the ground that is 4 feet long. If the shadow of an electric post is 10 feet long, what is the height of the electric post? SOLUTION Step 1: Translating the sentence “10 feet tall casts a shadow on the ground that is 4 feet long”...
如图所示，电源电动势为E，内电阻为r．两电压表可看作是理想电表，当闭合开关，将滑动变阻器的触片由右端向左滑动时，下列说法中正确的是（ ） A．小灯泡L1、L2均变暗 B．小灯泡L1变亮，V1表的读数变大 C．小灯泡L2变亮，V2表的读数变大 D．小灯泡L1变暗，V2表的读数变小 答案...
Under a Creative Commons license open accessHighlights Abstract This research is about how farmers adapt to water scarcity. Using experimental economics methods, field experiments were carried out in a region exposed to severe water scarcity in Colombia. Willingness of water users to cooperate in confo...