桥式起重机在定期检查中发现制动器摩擦衬带磨损量超过原厚度的（）%时应更换。
A.50
B.40
C.30
D.20
参考答案：A
It was reported that nine Chinese people ______ in a balloon crash (坠毁） in Egypt on February 26,2013. [ ]
A. are killed
B. were killed.
C. will kill.
D. have killed.
某种利胆解痉药的有效成分是“亮菌甲素”，其结构简式如图所示。关于“亮菌甲素”的说法中，正确的是
A．“亮菌甲素”可以与乙酸发生酯化反应
B．“亮菌甲素”的分子式为C12H12O5
C．1 mol“亮菌甲素”最多能和2 mol NaOH反应
D．1 mol“亮菌甲素”最多能和4 mol H2发生加成反应
