Answers

2016-01-21T20:03:28+05:30
Influenza is caused by various viral strains.Three types of influenza viruses are recognized : A, B and C. Type A is more common.
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2016-01-21T20:04:33+05:30
it is caused by 3 types of influenza viruses:A,B,andC.A is the most common.Influenza is known also as flu.
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