第7题: [单项选择]北方沿海地区修建有抗冰冻、防海水侵蚀要求的大坝工程,其混凝土可添加( )。 A. 纤维素醚 B. 木质素磺酸钙 C. 胺盐及衍生物 D. 改性木质素磺酸类 参考答案:D 答案解析:[解析] 木质素磺酸盐类、胺盐及衍生物、纤维素醚等缓凝剂用于炎热气候条件,改性木质素磺酸类引气减水剂可以解决混凝土遭受冰冻、海水侵蚀等作用时的耐久性问题。
第20题: [单项选择]A. He refused to take Linda with them. B. He agreed to take Linda with them. C. He thought Linda should decide herself. D. He thought Linda should write something. 参考答案:B 答案解析:[解析] W: I suggest we take Linda with us. What do you think M: Whatever you decide is alright