大家发现有一瓶溶液的标签已经破损，叶老师告诉同学们以上试剂均放置了较长时间并让大家对该溶液进行探究．

【提出问题】标签破损的溶液的是什么？

【设计实验1】小龙同学取该溶液少许于试管中，滴加酚酞溶液，变红色，于是认为是氢氧化钠溶液和碳酸钠溶液中的一种．

某大学的8名同学准备拼车去旅游，其中大一、大二、大三、大四每个年级各两名，分乘甲、乙两辆汽车.每车限坐4名同学(乘同一辆车的4名同学不考虑位置)，其中大一的孪生姐妹需乘同一辆车，则乘坐甲车的4名同学中恰有2名同学是来自于同一年级的乘坐方式共有（）

    One day a lion met a spider, who was just busy making a web. The lion 1 for a while and said, "How clever you are! How did you learn to do that?" The spider answered proudly, "I learned it from my mother."

    The lion watched a longer while. Then he asked the spider, "But why don't you catch your food in the way that I do?"

    "I am just a 2 animal," the spider replied. "I cannot run fast or fly. 3 with my web I can catch flying insects, and I don't even have to run after them."

    The lion then asked, "Could you make a 4 for me? Then I would not have to run after animals either."

    "Sorry," the spider said. "My web can only catch flying insects. But you cannot love 5 them."

    The lion was angry with the spider. She did not have to work 6 for food. And she would not help him get his 7. So he hit the web and broke it. But the spider jumped 8 the lion's back and bit him.

    "Now you will 9 me," said the spider as she jumped into the grass. "Think carefully 10 you do something bad to other animals. Some of us may be small, but we are very smart."

    The lion tried to scratch his back, but he could not reach where the spider bit. It itched(发痒)for several days. He remembered the smart spider for a long time.

如图，把一块含有45°角的直角三角板的两个顶点放在直尺的对边上．如果∠1=20°，那么∠2的度数是（    ）