2 . The British entrepreneur Richard Branson has successfully flown to the edge of space and back in his Virgin Galactic passenger rocket plane, days ahead of a rival launch by Amazon founder Jeff Bezos, as the billionaires compete to kick off a new era of space tourism. Seventeen years after Branson founded Virgin Galactic to develop commercial spacecraft, the space plane went into sub-orbital flight on Sunday morning, reaching 88 km above the Earth’s surface.

“Welcome to the dawn of a new space age,” Branson tweeted (发推特) shortly after the flight. Branson is the first of the competing “billionaire space barons”, and the flight can be served as a huge stunt (噱头) of advertisement for Virgin Galactic. In nine days’ time, Bezos will launch his own rocket, New Shepard — named for Alan Shepard, the first American astronaut in space, which was manufactured by Bezos’s company Blue Origin. On Saturday, Blue Origin tweeted a message of good luck to Virgin Galactic, after laughing at the company on Friday, when it came to whether Unity 22 was really going into space, instead of just to the edge of space.

The boundary between Earth’s atmosphere and outer space, known as the Kármán line, has been a source of controversy for years. Aeronatics standard setter Fédération Aéronautique Internationale defines the Kármán line as the altitude of 100km above Earth’s average sea level, However, US space agency NASA says the boundary is 80km, above sea level.

Interest in space tourism is rapidly catching on. Virgin Galactic says it has more than 600 reserved seats at $250,000 each for people who will fly in the future. The company plans to launch two additional flights before commercial service begins in 2023.

1. Why is Amazon founder Jeff Bezos mentioned in Paragraph 1?

A．To present his achievement.	B．To introduce the following topic.
C．To make a comparison with Branson.	D．To give an explanation of space tourism.

2. What does Branson’s initial flight mean?

A．Act as an advertisement.

B．Launch an rocket plane.

C．Gain a good luck message.

D．Make fun of Blue Origin.

3. Which is controversial among scientists?

A．Earth’s atmosphere.

B．The Kármán line.

C．The altitude of outer space.

D．The Earth’s average sea level.

4. What can we know about Virgin Galactic’s space tourism?

A．Over 600 reserved seats will be provided.	B．Tourists can get two extra flights.
C．Commercial service has begun.	D．250,000 people can fly to space in 2023.