选项
宏观事实
微观解释
A
水通直流电分解生成氢气和氧气
水分子含有氢分子和氧分子
B
空气中含有氮气和氧气
混合后它们的化学性质都已改变
C
二氧化碳气体制成干冰
分子间的间隔变小
D
20mL水与20mL酒精混合后体积小于40mL
分子数目减少了
A:A
B:B
C:C
D:D
△ABO与△A1B1O在平面直角坐标系中的位置如图所示,它们关于点O成中心对称,其中点A(5,2),则点A1的坐标是( )
阅读理解
Everyone surfing the web has billions of choices on what they can be viewing. And always we can find many different kinds of ads. Some of them are annoying, but some of them are useful. Here are some ads from the Internet. Maybe they are helpful for you.
House For Sale
Century Garden, Hangzhou
3-story house, 509sqm(平方米) total land area, 428.8sqm built-in, 312.2sqm garden. Asking ¥13 million($1.57 million)
If you are interested in the house, please contact the Housing Center.
MP:13861973547 Tel : 0571-89609228
Fax:0571-89609728
Job Wanted
Cherry, 24, a shining girl, is good at oral English and Putonghua. Now she is working at a trade company in Hangzhou. She is kind-hearted, hard-working and healthy. She would like a part-time weekend job offering Putonghua lessons to foreign friends.
Her e-mail address :Cherry if @hotmail.com
Daming Mountain Ski Resort
Price:55yuan (entrance ticket 门票).
150yuan /hour on weekdays and 285yuan /hour on weekends.
150yuan more for another hour on weekdays and 220yuan more for another hour on weekends .
Tel:0571-85502887
为响应“低碳生活”的号召,小明每天骑自行车上学,他看到路边的小树向后“飞过”,是以 ____为参照物的;在上坡过程中,其重力势能 ____(选填“增大”“减小”或“不变”);如果他在平直的公路上骑过3千米用了10分钟,则他骑车的速度为 ____ 米/秒.