第4题: [单项选择]阿司匹林在湿润和较高温度条件下,可发生颜色变化,是因为() A. 阿司匹林遇湿气水解生成水杨酸,水杨酸是有色物质 B. 阿司匹林在高温条件下被氧化 C. 阿司匹林遇湿气水解生成醋酸,醋酸在高温下被氧化生成有色物质 D. 阿司匹林遇湿气水解生成水杨酸,水杨酸在高温下被氧化生成有色物质 参考答案:D
第14题: [单项选择]Experiments in the photography of moving objects () in both the united states and Europe before 1990. A. have been conducting B. were conducting C. had been conducted D. are conducted 参考答案:C 答案解析: