混凝土立方体的抗压强度是由其( )测定的。
A．抗压极限强度B．抗拉极限强度C．抗压标准强度D．抗拉标准强度
参考答案：A
There was a _____ look on his face. He found what the expert said too difficult to understand.
A．puzzle
B．puzzling
C．puzzled
D．to puzzle
美国的乳畜业带分布在[ ]
A．西部山地草原区
B．五大湖区
C．南部墨西哥湾沿岸
D．中部草原区
