单项选择题

Airborne germs are ______ yet surprisingly few are virulent; despite the fact we inhale them with nearly every breath, the vast majorities of them are innocuous and are neutralized easily by our immune system.

A．ubiquitous
B．intolerable
C．omnipresent
D．plentiful
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单项选择题
The attempt and offer to carry out cloning experiment on human being is blameworthy and can hardly find any ______among the public not only in our country but also in most of the countries in the world.
A．conscience
B．consensus
C．sensation
D．discord
单项选择题
The cells contribute to immune defenses in two major ways: some direct and ______immune responses whereas others directly attack infected or cancerous cells.
A．regulate
B．activate
C．retain
D．consolidate
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