钝角三角形的外心在（    ）

为了研究植物的呼吸作用，某同学设计了如图的实验装置（装置气密性良好）．

①实验时，广口瓶用不透光的黑纸包住，其目的是为了防止瓶内的植物进行光合作用，对实验产生干扰；

②经过一段时间后，可以看到细玻璃管中的红墨水向右移动；

③实验结束后，揭去广口瓶外的黑纸，可观察到广口瓶中的澄清石灰水变浑浊．

上述说法中，正确的是（　　）

    Have you been asked for money by some disabled beggars (乞丐) while you're enjoying shopping? Do you have any pity on them who are so poor and lonely or do you just feel afraid of their terrible shapes? As one of the most special groups, disabled people's living conditions — not only their material (物质的) conditions, but their mental (精神的) world — really need improvement.

    The treatment for disabled people should go like this: First, don't look down upon them. Don't be afraid of looking at the terrible shapes of the disabled. Try to treat them equally. Because they are a part of the society (社会),we cant discard (抛弃) them. The second is to help them as much as we could. If you can be a volunteer and do some work for the disabled people, that would be very nice. That does help not only to the disabled people but also to yourself because you will feel good after your kind action.

    If every one of us gives a little love, the world will become a beautiful wonderland!