近年来，“晒黑族”异军突起，他们将社会上的不平事在网上进行披露，以警醒其他网民或政府部门，推动问题的解决。“晒黑族”的一个口号就是：“只有不想晒的，没有不能晒的。”对“晒黑族”的行为认识正确的是( )
①拓宽了公民直接管理国家事务渠道
②有利于改进政府工作，维护社会正义
③是公民参与民主决策的途径，是社会进步的表现
④必须坚持权利与义务统一的原则，做到有序参与

阅读短文，根据短文内容回答下面的问题。

    What do you do on weekends? Some people like to stay at home, but others like to leave home and do other things. My friend, Tom works hard in a factory. He has a son and a daughter.

    On weekends, he usually does the same things. On Saturdays he washes his car and clothes. On Sundays, he goes to a farm with his family by car. His parents live there. The farm isn't very big, but there're often many things to do on the farm. The children help feed (饲养) the animals. There are many animals on the farm. You can see sheep, cows, horses and pigs. Tom and his wife help in the fields. At the end of the day, children are very tired and hungry. Tom's mother gives them a big meal. They are very happy.

在临床上常常通过膝跳反射诊断患者的神经系统是否受损或患病．如图是该反射的示意图，请据图回答下列问题：

资本主义在世界的扩张逐渐淡化自然形成的地理界线，文化也免不了受外来影响，但有艺术家强烈要求摆脱外国文化控制，保持民族特色。以下符合这种时代要求的代表人物及作品是（   ）

用一支带有注射针头的玻璃注射器，抽动活塞吸入乙醚少许（约1-2mL））．取下针头，套上橡皮帽．使乙醚被封闭在注射筒内，抽动活塞。可以透过玻璃发现液态乙醚消失．乙醚成为气体：松开活塞并压缩活塞，发现液态乙醚又出现了。

乙醚是无色透明的液体，有特殊刺激性气味，带甜味，极易挥发。在空气的作用下能氧化成过氧化物、醛和乙酸，暴霹于光线下能促进其氧化。当乙醚中含有过氧化物时，在蒸发后所分离残留的过氧化物加热到100℃以上时能引起强烈爆炸：这些过氧化物可加5%硫酸亚铁水溶液振摇除去．与无水硝酸、浓硫酸和浓硝酸的混合物反应也会发生猛烈爆炸。乙醚溶于低碳醇、苯、氯仿、石油醚和油类．微溶于水．熔点-116.3℃．沸点34.6℃；易燃，低毒。