阅读理解
Our country used to be very poor in technology, but great changes have taken place these years. Lots of our technology is much better than those of foreign countries. High-speed railway technology is one example.
We learned about high-speed railway technology from foreign countries, but now we have mastered(掌握）and developed the key technology. Our high-speed railway technology is advanced. It can not only have a high speed but also be used in different environment and the cost is lower.
China Railway Corp (CRC) is fully prepared to sell a full supply of high -speed railway technology. The company said selling of railway technology and building railways for other countries are going very well, and progress is being made in a number of countries. We have a major advantage. We are able to sell whole railway technology. It isn't very good to buy some technology from one country and other technology from another.
The selling plan for our high-speed railway technology will follow the Silk Road Economic Belt and the 21st Century Maritime Silk Road (一带一路).
Like the US-made Boeing 737 and France's Airbus, our high-speed railway technology could be an important project to help sell our technology in the future.
，输出电压
=0。系统加速时滑块移动，滑片随之在变阻器上自由滑动，
，则这段时间导弹的加速度
