What does the example of three cars explain for? (). A: Unmanned vehicles are much better than manual in term of safe<br/>distance. B: Unmanned<br/>vehicles are much better than manual in term of reaction time. C: Unmanned vehicles can greatly reduce greenhouse gas emissions. D: Unmanned vehicles can greatly increase greenhouse gas emissions.

As its name suggests, a space elevator is designed to raise things into space.

Which of the following statement about China’s development in aerospace is NOT true? () A: China is the third<br/>country – out of 60 nations that engage in space programs –<br/>to independently send humans into space. B: The first manned<br/>docking in space with the Tiangong-2 space station has been realized C: China made a big<br/>breakthrough in space exploration at the beginning of the 21st<br/>century. D: Tiangong project<br/>is about sending human to the moon.

What<br/>are space agencies and companies aiming to do at present?() A: Recycle used space vehicles before they turn into debris. B: Develop technology to address the space debris problem. C: Limit the amount of debris entering space. D: Cooperate closely to retrieve space debris.

The Shenzhou VI spacecraft is the first manned spacecraft launched by China. At 9 o’clock on October 15th, 2003, the spacecraft carrying the space dreams of the Chinese was launched with Chinese astronaut Yang Liwei at the Jiuquan Satellite Launch Center.