单项选择题

IPM is different from the older methods because______.

A．chemical poisons are only used when necessary
B．chemical poisons are used very often
C．pests are completely destroyed
D．farmers do not have to worry about pests

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热门试题

单项选择题

UNEP has found______.

A．182 resistant pests
B．223 resistant pests
C．228 resistant pests
D．364 resistant pests

单项选择题

It is implied in Paragraph 2 that years ago governments______.

A．paid much attention to the results of scientific discoveries
B．seldom introduced safety laws before disasters occurred
C．hardly ever looked into the causes of tragedies
D．imposed safety rules as soon as disasters occurred