玩具检测的重点是( )。
A．安全性能检测
B．品质检验
C．包装检验
D．以上都是
参考答案：A
______ I studied harder, I could have passed examination. [ ]
A. Had
B. Were
C. Should
D. Did
亚里士多德对西方政治学的开创性贡献有哪些？
