单选题 Atoms (原子) are all around us. They are the bricks of which everything is made. Millions of atoms are held in just one grain of salt, but in spite of their small size they are very important. The way an everyday object acts depends on what kind of atoms are in it and how they act.
For example, you know that most solid objects melt (熔化) if they get hot enough. How does it happen? It is the effect of the heat on the object's atoms. All atoms move constantly. When they are hot, they move faster.
Usually the atoms in an object hold together and give the object its shape. But if the object grows hot, its atoms move so fast that they break the force that usually holds them together. They move out of their usual places so that the object loses its shape. Then we say that the object is melting.

单选题 Atoms are like bricks because ______ .

【正确答案】 D

【答案解析】本题题干问“为什么原子像砖一样”。原文第1段第2句话指出原子是组成的所有事物的基本元素。因此选项D. everything is made of atoms是正确答案。

单选题 The way one object acts depends on ______.

【正确答案】 D

【答案解析】本题题干问“一个物体的运动是依靠什么”。原文第1段第4句话指出物体的运动依靠的是物体内部原子的种类和原子的运动这两个因素。因此选项D. both B and C是正确答案。

单选题 Atoms in an object move ______ .

【正确答案】 A

【答案解析】本题题干问“一个物体内部原子是如何运动的”。原文第2段第4句话指出原子是在不断地运动的。因此选项A. all the time是正确答案。

单选题 When the atoms of an object leave their usual places, we say that the object is ______ .

【正确答案】 D

【答案解析】此题题干问“当一个物体的原子离开原先的位置，我们如何来形容这一变化”。原文第3段第3和第4句话指出当一个物体的原子离开原先的位置导致该物体变形，这种变化称为熔化。因此选项D. melting是正确答案。

单选题 Which of the following is NOT TRUE?

A、 We have atoms all around us.
B、 All atoms are moving.
C、 There are millions of atoms in only one grain of salt.
D、 When heated, an object will hold together and give its shap

【正确答案】 D

【答案解析】本题测试辨认正确信息的能力。原文第3段第2句话指出当物体变热，它的原子运动就会变快，因此就会超越原先让它们聚集在一起的力。因此选项D. When heated, an object will hold together and give its shape. 与原文意思相反，是正确答案。