在滑冰场上，甲、乙两小孩分别坐在滑冰板上，原来静止不动，在相互猛推一下后分别向相反方向运动．假定两板与冰面间的动摩擦因数相同．已知甲在冰上滑行的距离比乙远，这是由于（   ）

读短文，判断对错。
    My name's Alice. Look at my classroom. It's big and clean. The floor is green, the walls are white. The door is yellow and the windows are blue. Two pictures are on the wall. They are beautiful. How many lights are there? Nine! My desk is near the door. My schoolbag is on the desk. What's in my schoolbag? A pencil box, an English book, a maths book, a Chinese book, three storybooks and five notebooks. I like my classroom. I like my schoolbag too.

下列有关声音的情境说法错误的是（  ）

下列变化中，属于物理变化的是（  ）

已知复数z₁=34i, z₂=1+i，则复数对应的点在第（   ）象限.