瓦斯爆炸的最高浓度16%,称为爆炸上限；瓦斯爆炸的最低浓度5%,称为爆炸下限。
参考答案：对
根据ERG里论，下列说法正确的是( )。
A．该理论提出三种核心需要：生存需要、安全需要、成长需要
B．各种需要可以同时具有激励作用
C．如果高层次的需要得不到满足，对低层次需要的欲望也会降低
D．该理论的独特之处在于认为低层次需要的满足是高层次需要的先决条件
Not until Dec. 2003 _____ caught by the US soldiers, and it was a great victory for the USA. [ ]
A. was Saddam Hussein
B. Saddam Hussein was
C. had Saddam Hussein been
D. Saddam Hussein had been
