下列对生物进化总体趋势的描述不正确的是（　　）

 

下列区分物质的方法不正确的是 

    Have you ever heard an echo of your voice?
    An echo is a reflected(反射)sound. Stand in a very large, empty hall with nothing on the walls. Then shout. The sounds you make will hit the walls and come back to you. The walls reflect the sounds. These reflected sounds are called “echoes”.
    We can use reflected sound to make sound travel farther. Hold a watch about fifty centimeters from your ear. You cannot hear it. The sound of the watch travels a short way in all directions. It does not travel as far as your ear. You can make it travel to your ear by using a roll of cardboard(纸板筒).
    Make the roll of cardboard about fifty centimeters long. Put one end over your ear and hold the watch at the other. Now you can hear the watch because the sound has not gone in all directions. It is reflected down the roll to your ear.
    A megaphone(喇叭筒)works in the same way. It makes sound travel farther. It reflects the sound into a beam which can travel a long way. In the ship, the sailor uses the megaphone to make his voice travel. Without the megaphone, his voice cannot travel far.
    We use reflected sound in many ways. We use it to measure the depth of the sea, for example. Among the animals, bats and whales use reflected sound to tell them where they are and what things are near them.

图甲为有丝分裂过程中细胞核DNA含量变化的曲线图，图乙为有丝分裂各时期图象（未排序），图丙是洋葱根尖结构图，请完成下列问题：

一名全国政协委员长期关注流浪乞讨未成年人的救助保护问题，经过大量调查研究，他在2011年“两会”期间提交了提案《关于加强流浪乞讨未成年人救助保护的建议》。年底，民政部对该提案作出了书面答复，其切中时弊、言之有物的建议得到不同程度的采纳并正在转化为相关政策。这说明，政协委员的建言献策(　　)
①是人民行使国家权力的形式　②是国家科学决策的重要依据　
③转化为政府政策是有条件的　④体现了政协对政府负责原则