Ponds and lakes form when water collect in areas of land

Check all that apply diatoms are marine algae that have a shell made of silica, what are some of the uses of the silica shell after the diatoms die? 1.the shells make up the diatomaceous earth used in filters 2.it can be used as an ingredient in abrasives 3.they are used in food products 4.the shells can be used in some insulating materials

What term describes a doctor who becomes a specialist by meeting standards beyond those of getting a license and passing a test in the specialty area?

What does the number 18.9984 represent in the image?