当所输配的燃气掺混其他种类的燃气或被另一种燃气所取代，则燃气的燃烧性能会发生很大变化，要使原有的用气设备的热负荷不变，又能保持良好的燃烧性能，必须考虑燃气的（）
B
暂无解析
翻译：WorldWarIIwasmorecomplexthanWorldWarI,whichwasacollisionamongtheimperialistpowersoverthespoilsofmarket,resourcesandterritories.
Intheoriginaltest，alltheanimalsinatestgrouparegivenasubstance_______halfofthemdie
“Woman”becomes“Frau”inGerman,“femme”inFrenchand“fùnǔ”inChinese.Thisexampleshowsthatindifferentlanguagesthesameconceptcanberepresentedbydifferent______.
TheMississippi,whichissometimescalled________,hasplayedavitalroleinthehistoryoftheUnitedStates.