How long can spark plugs last? There are two types of spark plugs: conventional and long-life (platinum- or iridium-tipped). Conventional spark plugs need to be replaced every 30,000-50,000 miles. Recommended replacement intervals for iridium- or platinum-tipped spark plugs vary between 50,000 and 120,000 miles. To find out the recommended replacement interval for your car, check your maintenance schedule.
Its key principles: (1) the three primary colors are red, yellow and blue, (2) the primaries exist as three material substances (often identified with specific pigments), (3) the primaries cannot be mixed from other colors, but can mix all other colors.
Yellow is NOT a primary color of light! When I was in first grade I was presented with a distressing problem for a 6 year old. My father, a television technician, had taught me that the primary colors are Red, Green and Blue. My teacher insisted that it was Red, Yellow and Blue. A few years later as my reading level increased I hit upon the answer - both are right depending on what you are talking about. Red, Yellow and Blue are the primary colors of pigment. But Red, Green and Blue are the primary colors of light. If you are coming to web page design from a print background this distinction is very important to learn because color codes on the web mix light, not paint. In CSS you've no doubt ran across color codes.