题目

将等体积的AlCl3溶液和NaOH溶液混合后，沉淀物中铝元素的物质的量与溶液中铝元素的物质的量相等，则原AlCl3溶液与NaOH溶液的物质的量浓度之比可能是( ) A . 1：3 B . 2：5 C . 1：5 D . 2：7 答案：DHow fit are your teeth? Are you lazy about brushing them? We brush our teeth every day but few people know how well we're brushing. Today, a French company has introduced an electric toothbrush, which can work wirelessly（无线地）with a smartphone. It's called the Kolibree toothbrush. It has different models, and will cost from$99 to$200 .The US is the first target market.Users download an app and connect via Bluetooth, and the Kolibree will record: 1 .the time you spent brushing teeth. 2.whether all areas of your mouth are reached. 3 .whether you brush up and down instead of just side to side. Then it will send the information to a mobile phone via Bluetooth, telling you whether you have brushed in a proper way. The Kolibree records your progress and scores your brushing way to help you improve brushing habits. It's kind of like having a private dentist actually watch your brushing on a day-to-day basis. The toothbrush can also talk to other apps on your phone, so developers could create a game controlled by your toothbrush. When you brush your teeth, you can score your points for beating the monsters in your teeth. That's really very interesting. The Kolibree toothbrush is created to be smart but also fun. The Kolibree toothbrush was invented by Thomas Serval. He says the idea of inventing it came from his experience as a father. He would come home from work and ask his kids if they had brushed their teeth. They always answered "yes", but Thomas used to find their toothbrush heads dry. He decided that a kind of brush was needed to tell him how well they brushed their teeth. Thomas says that one day, it'll be possible to use a brushing unit with a camera. The camera can even examine holes in your teeth while you brush.【1】The Kolibree toothbrush was invented by_ .A. a French companyB. Thomas ServalC. Thomas Serval's father【2】How much is the Kolibree toothbrush?A. From$99 to$200.B. From$90 to$200.C. From$20 to$900.【3】What can the Kolibree toothbrush do?A. It can record how often you brush your teeth.B. It can tell you what time you should brush your teeth.C. It can score your brushing way.【4】What's the reason for inventing the Kolibree toothbrush?A. Its inventor was interested in toothbrushes.B. The toothbrush heads were too dry.C. Its inventor wanted to know whether the kids brushed their teeth.【5】What will the Kolibree toothbrush probably be like in the future?A. The Kolibree toothbrush will be able to talk to other apps.B. There will be a game controlled by the Kolibree toothbrush.C. A camera will be installed（安装）in the Kolibree toothbrush.