A standard contains a known amount of a substance. If u are performing an experiment you will use a sample with a known concentration to create a standard curve (a straight line). Positive and negative controls are measured against the standard curve to show the expected results if the sample u will be testing is positive or negative.
48 hours<span>Most plaque hardens within 48 hours of formation, and within several days it will become so hard that it is almost impossible to remove. This hard substance is tartar and the only way to remove it is to see your dentist for a professional scraping of your teeth.
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Answer:
I think sociallogy means the good and nice characters of people who live in society
<span>C-A-B: chest compressions first, then airway and breathing.</span>
He will usually have an accident if he drives, due to the depressant nature of alcohol
