In case you base your condition on the current date, you can use the TODAY() function in the logical_test argument of your IF formula. For example: Naturally, the Excel IF function can understand more complex logical tests, as demonstrated in the next example.
A sink mark is a local surface depression or void that typically occurs in moldings with thicker sections. They are also common in locations above ribs, bosses, or internal fillets. As the plastic cools at different rates in the mold, the surface hardens but leaves the thicker areas in the center still molten.
An electron sink is an atom on a molecule or ion that can accept a new bond or lone pair of electrons. Learning to identify the characteristic sources and sinks in different functional groups is the key to learning organic chemistry reaction mechanisms.