烟烙烬式气灭系统使用的混合气体的成份：（） A: 52% B: 40% C: 和8%CO D: 52% E: 40%Ar、和8%CO F: 52% G: 40% H: 和8%CO I: 52% J: 40%Ar、和8%CO

为什么f(36)等于f(4*9)等于f(4)加f(9)

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一个怀孕7～9个月的孕妇的标准人系数是（）。 A: 1.21 B: 0.888 C: D: 96 E: F: 85

钢琴键盘一共有88键，其中白键和黑键分别是多少个（）。 A: 52、36 B: 36、52 C: 88、52 D: 36、88

如图，直线AB∥CD，∠C＝36°，∠E为直角，则∠A等于（） A: 36° B: 44° C: 54° D: 64°

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