单项选择题

Hydrocarbons, ______ by engine exhausts, react with nitrogen oxides in the presence of sunlight to form complex toxic gases.

A．are given off
B．give off
C．they are given off
D．given off

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单项选择题

Nicholas Chauvin, a French soldier, aired his veneration of Napoleon Bonaparte so ______ and unceasingly that he became the laughingstock of all people in Europe.

A．vociferously
B．patriotically
C．verbosely
D．loquaciously

单项选择题

Whenever work is being done, energy ______ from one form into another.

A．converts
B．converted
C．is converted
D．is being converted

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