单项选择题

Some years ago safety rules （）

A．were put forward due to scientists' recommendations
B．came into being as a result of the workers' demand
C．were introduced because quite a number of people were killed or seriously injured
D．were effective enough to protect workers and customers

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单项选择题According to the passage, the sloth will move about when（）

A．it senses a coming danger
B．it is forced to swim on a hot day
C．it is short of its favorite food
D．it wants to keep itself to itself

单项选择题A suitable title for this passage might be（）

A．Wild Animals
B．Animal Kingdom
C．Moss Growth
D．The Lazy Animal