The main blood tests are leukocytes, neutrophils, lymphocytes, eosinophils, hemoglobin, red blood cells, platelets, etc. 1. If leukocytes and neutrophils are increased, it usually belongs to bacterial infection; if leukocytes are decreased and lymphocytes are increased, it usually belongs to viral infection. 2. If eosinophils are increased, it is usually seen in allergy, skin disease and parasitic infection. 3. Hemoglobin and erythrocyte decrease, mostly seen in various kinds of anemia, leukemia, etc. 4, thrombocytopenia, mostly seen in aplastic anemia, leukemia, after radiotherapy, etc. 4, thrombocytopenia, mostly seen in aplastic anemia, leukemia, after radiotherapy, etc. Thrombocytosis, mostly seen in chronic granulocytic leukemia, true erythrocytosis, primary thrombocytosis, etc.