下列有关分子、原子和离子的说法正确的是
A．原子是最小的粒子
B．物体有热胀冷缩现象，主要是因为物体中的粒子大小随温度的改变而改变
C．分子、原子、离子都可以直接构成物质
D．任何粒子都不能再分
答案：C
题目分析：原子由质子和中子构成，原子可以再分；物体有热胀冷缩现象，主要是因为物体中的粒子间间隔的大小随温度的改变而改变；分子、原子、离子都可以直接构成物质。选C。
点评：分子由原子构成，原子可以再分，原子得失电子形成离子；分子、原子、离子都可以直接构成物质。
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| Most adults once studied at school, had classes and did their homework every day. The same 1 is going on at school now. 2 it seems that doing weekend homework is another problem for the 3 students. All the students 4 that weekend homework should be abolished (取消). It is 5 for them to study at school five days a week. They have a lot of interests. 6 homework to do on Saturday and Sunday, when can they 7 time to help their parents do the housework, go and see a football or basketball game or a good 8 , join in family recreation (娱乐), or just have a rest at home? Because of these other activities, the homework can't be finished 9 Sunday evening. So their weekend homework is usually done in such a hurry that on Monday teachers are 10 and often threaten (威胁) to 11 the whole class of students because many of the students know 12 about the lessons. 13 there were no weekend homework to do, they would be 14 to go to school on Monday after 15 good rest and to learn what the teachers teach. | ||||
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