Students go hungry for charity（慈善）

    Students at New Point School enjoyed their breakfast today, for it broke a 24-hour fast（禁食） for charity. During the fast, they could not eat any food ____,and they could only drink water, tea and clear fruit juice. The students all volunteered to go without food for one day to raise money for UN projects to help the poor ____.

Mr. James Wood, their English teacher, said, “The students ____ the idea themselves after seeing photos of hungry children. They organized the whole thing. I'm very proud of them.”

    “Twenty-four hours did not feel like a very long time. Next year, I might even double ____ I spend fasting. Then I can raise twice as much money!” said Jane Austin, a student. “It's so wrong for us to have lots of food while many people in the world are going hungry. We need to give to those in need.”

    The students collected about $2 400 from the fast. They were ____ the total amount. “It's amazing! People are so kind, and they want to help others,” said Alan Long, another student.

下列说法正确的是（）

下列判断正确的是（　 　）

下列是有关实验试剂在实验操作中的应用：

（1）用海藻酸钠制成人工种皮，可以保护通过____ 技术获得的胚状体；作为包埋剂的海藻酸钠加热溶解后，冷却至室温再和一定浓度的酵母菌溶液混合，用注射器将混合液缓慢而匀速地注射到一定浓度的____ 中，一段时间后得到了固定化的酵母细胞．

（2）用上述过程获得的固定化细胞和一定浓度的葡萄糖溶液混合一段时间后，用　____ 检测其酒精的生成情况．若经过检测发现没有酒精生成，请分析其可能的原因有哪些？____ （写两点）．用上述固定化细胞发酵获得酒精后，再进行工业纯化，形成浓度为____ 的酒精溶液用于根尖的解离，形成浓度为____ 的酒精溶液用于提纯DNA．

（3）在DNA粗提取实验中配制浓度一般为____ 　的NaCl溶液溶解DNA，析出杂质．在豆腐乳的制作过程中加NaCl的注意事项是什么？____