The Yellow Mountain is one of the most famous m____  in China. Every year l____  of Chinese people and foreigners visit it. It is not f____  from here. You can s____ about two hours getting there by bus. You can also go there by train o____  by plane. When you are c____ the mountains, you can e____  the sea of clouds, wonderful trees and rocks (岩石) a____ you. In the e____ morning when the sun rises (升起)，the sun looks b____ . It is really a good place to go.

黄河是我国泥沙含量最大的河流，治理黄河水患的根本措施是

为了研究合力和分力的大小，甲乙两个同学做了如下实验，甲同学用拇指把栓校园卫士牌的轻质细绳用两手拉直，乙同学用一个手指轻轻一推，如图所示．关于这个实验，以下说法错误的是（   ）

若2a^3xb^y+5与5a^2-4yb^2x是同类项，则（      ）