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Chemist working in the lab on new experiment
A test tube with a test for h5n1 avian influenza. The concept of an avian flu pandemic. Checking the chicken for diseases.
Stressed student holding head while taking exam in high school classroom Tired girl showing signs of difficulty during test at secondary school. Classmates writing answers to the college entrance exam
Eco laboratory microbiology. Sample in a Microscope and comparing a plant or herb in test tube or glassware. Natural product and organic cosmetic health care.
Hydraulic press machine testing compression strength of concrete cube sample in material testing laboratory, determining its resistance to compression stress

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