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科学家发现在特定条件下，水能表现出许多有趣的结构和性质。一定条件下给普通水施加一个弱电场，在常温常压下水就能结成冰，俗称“热冰”，则下列说法中正确的是( )

A: 普通水结成“热冰”的过程中原子个数发生变化 B: “热冰”与普通水的化学性质不同 C: “热冰”在任何条件下都不会融化 D: “热冰”中氢、氧两种元素的质量比为1:8

Dear Sam,

Here are sonic (1) for you when your dad and I are not at home. (2) , get home early. Don't play (3) after school. Second, take care of(照顾) your brother and don't (4) with him. Third, help your grandma do the (5) after dinner. Fourth, remember to (6) the piano for one hour every evening. Fifth, go to bed (7) ten o'clock. The last one, (8) your room clean and don't leave your (9) clothes everywhere. Your dad and I will be very happy if you can (10) the rules.



(1) A. rules
B. books
C. clothes
D. classes
(2) A. Then
B. First
C. But
D. So
(3) A. in
B. hard
C. outside
D. quietly
(4) A. help
B. talk
C. learn
D. fight
(5) A. exercises
B. dishes
C. homework
D. lesson
(6) A. buy
B. see
C. practice
D. clean
(7) A. before
B. after
C. in
D. to
(8) A. remember
B. think
C. leave
D. keep
(9) A. dirty
B. nice
C. new
D. important
(10) A. make
B. follow
C. read
D. write

下列现象属于旋转的是（　　）
A: 摩托车在急刹车时向前滑动 B: 飞机起飞后冲向空中的时候 C: 笔直的铁轨上飞驰而过的火车 D: 幸运大转盘转动的过程

一平面内，三条直线两两相交，最多有3个交点；4条直线两两相交，最多有6个交点；5条直线两两相交，最多有10个交点；8条直线两两相交，最多有 几 个交点．

你好，问问问问

六边形的面积怎么计算

六边形内角和是多少

我想用图片提问

三角形的面积计算公式

假设排列着100个乒乓球，由两个人轮流拿球装入口袋，能拿到第100个乒乓球的人为胜利者。条件是：每次拿球者至少要拿1个，但最多不能超过5个，问：如果你是最先拿球的人，第一次拿几个能保证你能得到第100个乒乓球？

多边形内角和公式是什么？