题目内容：

China's lasting research and development efforts have helped the nation keep its pioneering role in developing 5G mobile communication technology, related standards and the licensing stage．

Chinese telecom companies are trying to keep their leading role in the global race for 5G commercialization（商业化）.They are speeding up R&D of the fifth-generation mobile communication technology. The 5G technology is said to be at least 10times faster than 4G services which means it will enable superfast downloads of " heavy " files like movies, self-driving cars and virtual（虚拟的）reality games. It will do large-scale experiments of using 5G in 17cities. Yang Jie, chairman of China Telecom, said. "We aim to begin commercial 5G services in 2020."

China Mobile Communications Corp is planning to use 5G with AI and cloud technology for a latest network, which is planned to be used in the year 2020. The company has played an important role in the finish of the first stage of global 5G standards. The company will push forward the cloud deployment（云部署） of the superfast technology and build an intelligent network.

Similarly, China Unicom said it will start 5G testing this year, commercialize 5G in 2019and finally carry out large-scale commercialization in 2020.

China is expected to have 576 million 5G users by 2025, according to a report published by EY earlier this month. With the global united standard set to be finished in the next year or so, China is likely to advance its plan for the commercial use of 5G connections to 2019, to possibly become one of the first 5G-ready markets in the world, EY forecast.

In the past, China was behind other countries in publishing 4G and 3G licenses. But in 5G, perhaps China will race ahead in R&D. China is struggling to take a leadership role in the global landscape. China is also hungry to join in the decision of 5G international standards, making it one of the major players.

1.The word "heavy" in the second paragraph refers to ______ ．

A. important    B. long    C. huge    D. valuable

2.What can we infer about the passage？ ______

A. China attaches great importance to the commercial application of 5G．

B. The large-scale experiments of using 5G will be done in 17 cities by China Mobile．

C. China lay behind other countries in using 4G and 3G in the past．

D. China will decide 5G international standards in the future．

3.According to EY forecast, the year when China plans the commercial use of 5G connections is likely to be ______ ．

A. 2018    B. 2019    C. 2020    D. 2025

4.The best title of this passage is ______ ．

A. The 5G technology in China

B. Three communication companies in China

C. The commercial use of 5G in China

D. Chinese carriers wrest （争夺） 5G lead