A. might have been; had helped B. could have been; helped C. was; could help D. must have been; help 参考答案:B 答案解析:[分析] 句意为:整栋楼可能都已经烧掉了,但幸亏那场大雨救了急。本题考查的是虚拟语气用法,could have been意为“有可能已经……”。例:If I hadn't warned you,you
第18题: [单项选择]十进制负数-38使用八位二进制补码表示为______。 A. 01011011 B. 11011010 C. 11011011 D. 01011010 参考答案:B 答案解析:[分析] 补码表示法规定:负数的补码是该数的反码的最低位加1。十进制数38的八位二进制原码是00100110,所以十进制负数-38的八位二进制补码是11011010。