已知O为△ABC所在平面内一点，且满足$\overrightarrow{OA}$²+$\overrightarrow{BC}$²=$\overrightarrow{OB}$²+$\overrightarrow{CA}$²=$\overrightarrow{OC}$²+$\overrightarrow{AB}$²，则O点的轨迹一定通过△ABC的（　　）

Julie: Are you OK, Bill? You look tired.

Bill: Tm fine, Julie. I just ____ (stay) up late last night to write an English article. It is time for me to improve my English writing.

Julie: Read as many things you're interested in as possible,____ soon you'll realise that there are many different ways of saying ____ same thing. After all, having a variety of sentence ____ (structure) in your writing makes your English appear better.

Bill: Reading can also broaden my vocabulary. What kind of books should I read?

Julie: You can choose books ____ (write) by native speakers. They, often contain sentences ____differ from those commonly seen in English textbooks.

Bill: Good idea. But sometimes I don't know what to write about and find ____ hard to write a long article.

Julie: I suggest you begin by writing short ones about topics you're interested in, such as movies and sports.

Bill: Yes, III write something every day.

Julie: Writing all the time is the key to improving your writing.

Bill: Quite right. Practice ____(make) perfect.

Julie: It's ____ (easy)said than done. But in the end, it's worth the work you've put in.

Bill: Thank you for giving me such ____ (value) advice.

根据下列材料，完成（1）-（3）题。

材料一  图1为我国西南部分地区略图。图2 为2014年重庆工业结构图。

材料二  成都和重庆是成渝城市群两大核心城市，成都电子信息产业发达，重庆工业基础雄厚。汽车为两城市支柱产业，成都以客车、商用车、轿车生产为主，重庆以重型汽车和轿车生产为主。在十三五规划中，两城市都把中高档轿车、新能源汽车和智能汽车做为发展重点。