题目

一___________________?    一Yes,please. I’d like some lemons.     A. Who are you                  B. What would you like to buy       C. How many lemons do you need  D. Can I help you 答案：D 4.6 g某物质在空气中完全燃烧，生成8.8 g二氧化碳和5.4 g水，则该物质中一定含有________元素，其质量比为________。