单项选择题

Why is the crew's task a high-stakes one

A．Because it has never been rehearsed.
B．Because space shuttle Columbia had a similar problem.
C．Because the new material has been used up.
D．Because the crew will have to work outside Discovery.

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单项选择题

What happened while Discovery was ascending

A．A large piece of debris flew off the tank.
B．A filler dropped from the ship's thermal tile belly.
C．The fuel tank started to leak.
D．It caught fir

单项选择题

What is the news mainly about

A．The gloomy local economy.
B．The release of government data.
C．The budget report from the Commerce Department.
D．The rise of local incomes.