单项选择题

According to the passage glass cools and becomes rigid differently from metals because ______.

A．it has an unusually low melting temperature
B．it does not set up a network of inter3ocking crystals
C．it has a random molecular structure of a liquid
D．it is made from a mixture of silica, lime, and soda

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单项选择题

Glass can be easily molded into all kinds of forms because ______.

A．it melts like liquid when heated
B．it softens gradually through varying stages when heated
C．it retains the shape at the point when it is suddenly cooled
D．various heating techniques can be used in making glass

单项选择题

Which of the following statements is NOT TRUE

A．Dr. Urbani caught SARS from an American businessman who was hospitalized in Hanoi.
B．There were not enough disposable masks, gowns, gloves and protective equipment.
C．He knew he had little hope to survive after he was found infected.
D．Dr. Urbani had helped combating the new disease by putting in place a series of infection-control measures.