What invention did the Chinese keep secr...r hundreds of years?
举一反三
- Paper was a Chinese invention and it was invented ______（填数字，勿填单词） years ago.
- 中国大学MOOC: What did the invention of the World Wide Web lead to/
- What did Chinese people believe in the past?
- We can hardly __________(想象)what it felt like to live the beautiful area hundreds of years ago.
- What did the third worker become after 20 years?