简述遥感三要素。
穿越铁路的燃气管道的套管应满足的要求有()。 ["套管两端与燃气管的间隙应采用柔性的防腐、防水材料密封","套管宜采用钢管或钢筋混凝土管","套管端部距路堤坡脚外距离不应小于1.2m","套管内径应比燃气管道外径大150mm以上","铁路轨道至套管顶的埋设深度不应小于2.0m"]
预留多少现金,主要可以根据()因素。 ["风险偏好程度","持有现金的机会成本","现金收入来源及稳定性","现金支出渠道及稳定性","非现金资产的流动性"]
某植物茎木质程度不高,且较柔软,第一年种子发芽生长,第二年开花,结实后死亡,则茎的性质为()。 ["灌木","一年生草本","多年生草本","两年生草本"]
11. class Cup { } 12. class PoisonCup extends Cup { } 21. public void takeCup(Cup c) { 22. if(c instanceof PoisonCup) { 23. System.out.println(”Inconceivable!”); 24. } else if(c instanceof Cup) { 25. System.out.println(”Dizzying intellect!”); 26. } else { 27. System.exit(0); 28. } 29. } And the execution of the statements: Cup cup = new PoisonCup(); takeCup(cup); What is the output?() [" Inconceivable!"," Dizzying intellect!"," The code runs with no output."," An exception is thrown at runtime."," Compilation fails because of an error in line 22."]
自动调节系统的主要特点是什么?