在向前行驶的汽车里看外面的景物在向后移动。（  ）  

如图所示是小明家的电热水壶及铭牌，他用该电热水壶将1.5kg的水从20℃加热到100℃．

（1）水吸收的热量是多少？〔c_水=4.2×10³J/（kg•℃）〕

（2）若电热水壶正常工作，且产生的热量全部被水吸收，需要加热多少时间？

划分发达国家和发展中国家的依据是（　　）

把下面的图片与所给的描述对号入座。
A        B          C 
D                E
____ He is of medium height and build, with two small eyes. He is a pop singer. And he likes playing basketball very much. He is very popular with young people.
____ He is short and of medium build. He has short black hair. He is a funny actor.
____ She is heavy. She has short brown hair. She always wears glasses. She sings very well.
____ He is very tall and has short black hair. He is a basketball player, and he plays it very well. Now he is a college student in Shanghai Jiaotong University.
____ She is thin, with long black hair and big eyes. She is a movie star. She is in the play "Palace", and she is very popular with young people.

汉武帝时期，为了适应和平年代的需要，中央和地方官府向社会征聘人才的制度是指