单项选择题

What does the passage mainly discuss

A．Causes of food spoilage.
B．Commercial production of ice.
C．Inventions that led to changes in the American diet.
D．Population movements in the nineteenth century.

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热门试题

单项选择题

The author implies that in the 1920s and 1930s home deliveries of ice ______.

A．decreased in number
B．were on an irregular schedule
C．increased in cost
D．occurred only in the summer

单项选择题

It can be inferred that railroad refrigerator cars came into use ______.

A．before 1860
B．before 1890
C．after 1900
D．after 1920