图示叶芽的结构，下列关于叶芽的叙述中正确的是（　　）

完型填空。

    My name 1Tim. I'm 16 years old. I'm a junior high school student. Tomorrow is the weekend. We have no classes. My parents2 going to work, but we are going to be very busy tomorrow. My mother is going to buy a sweater 3my grandmother. My father is going to visit my aunt and uncle. I'm going to4computer games with my cousin. Tomorrow evening we are going to have 5big dinner. After dinner we are going to the cinema to see a film by car. I think we are going to have a nice weekend.

主要的遗传物质是指(     )

某化学兴趣小组在化学实验室发现一瓶没有标签的淡黄色粉末，同学们对探究该粉末产生浓厚兴趣，并在老师的指导下进行探究活动．

【提出问题】这种淡黄色粉末是什么？有什么性质和用途？

【查阅资料】①硫是一种、淡黄色粉末，不溶于水且不与水反应；

②过氧化钠（Na₂O₂）是淡黄色粉末，在常温下能与水反应生成极易容于水的氢氧化钠和一种无色无味的气体；

③过氧化钠在常温下能与二氧化碳反应生成碳酸钠和氧气，其符号表达式为：CO₂+Na₂O₂→Na₂CO₃+O₂．过氧化钠在呼吸面具中和潜水艇里常用作供氧剂．