【判断题】电导为9S和18S的两个电阻并联等效电导为27S。
【单选题】Is oxygen the only gas that ___ fire burn?
【单选题】Is oxygen the only gas ______ helps to burn?
【单选题】Is oxygen the only gas______helps fire burn?
【简答题】Is oxygen the only gas _______ helps fire burn?
【单选题】Is oxygen the only gas ________ helps fire burn?