阅读判断。
    Hello, my name is Tom. I like English very much. My favourite food is beef, rice and tomato. I'm very helpful. I can clean the room and wash the clothes. Today is Saturday. I often read books, do homework and watch TV.
    My home is near a river. There are some mountains behind my house. There is a tree in front of my house. You can see two bridges over the river.

黄土塬是我国黄土高原主要的地貌景观，如图为某黄土塬等高线图。读图完成下题。

某同学做“探究功与速度变化的关系”的实验，如图所示，小车在一条橡皮筋的作用下弹出沿木板滑行，这时橡皮筋对小车做的功为W．当用2条、3条…实验时，使每次实验中橡皮筋伸长的长度都保持一致，每次实验中小车获得的速度都由打点计时器所打的纸带测出．

人类进入20世纪90年代后，科学技术获得了巨大的发展，但在某些领域这种发展甚至与当代的社会伦理观念发生了激烈的冲突，这一冲突最突出的表现是（   ）

设N_A为阿伏加德罗常数，下列有关说法正确的是（      ）