叶球内球球内叶先从叶缘黄化变干，逐步变干，逐步扩展，叶肉呈干纸状，叶片皱缩或心叶干腐是由（）造成。
参考答案：缺Ca
根据图片所示内容填空。
1. Uncle Da Chao is my father's _______________.
2. Jing is my _______________.
3. Jing is my uncle Da Chao's _______________.
4. _______________ Mei Ping is my _______________ Da Chao's _______________.
5. My father and uncle Da Chao are my grandfather's _______________.
如何配制硫酸溶液？
