单项选择题

Judging from the context, the word "they" (Line 2, Para. 4) refers to______.

A．the security risks
B．the terrorist attacks
C．environmental hazards of over-centralization
D．the security risks, economic expenses, and environmental hazards

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单项选择题

What is the author’s attitude towards the reconstruction of The Pentagon and the World Trade Center

A．Supporting.
B．Critical.
C．Neutral.
D．Hostile.

单项选择题

The advantage of telecities over megacities may include all the following EXCEPT______.

A．reducing pollution
B．conserving energy
C．high cost of urban property
D．helping to deal with terrorist