单项选择题

The word "immunization" (Lines 2, Para. 5) probably means _________.

A．state of being infected seriously
B．state of being polluted seriously
C．stafe of being made resistant to a war
D．state of being made resistant to a disease

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热门试题

单项选择题

According to the passage, the exchange of medical ideas between east and west started ________.

A．thousands of years ago
B．decades of years ago
C．a few years ago
D．after the Second World War

单项选择题

What conditions are needed for shrubs to become established

A．Ferns must take root.
B．The ground must be covered with grass.
C．More soil must accumulate.
D．Smaller plants must die out.