What is the present perfect continuous tense

The greenhouse effect is a process that occurs when gases in Earth's atmosphere trap the Sun's heat. This process makes Earth much warmer than it would be ... Engineers are experts in their fields, creating and innovating constantly. As practitioners of engineering, engineering professionals deal with complex systems, ... The 504 Plan is a plan developed to ensure that a child who has a disability identified under the law and is attending an elementary or secondary educational ... A neurologist is a medical doctor with specialized training in diagnosing, treating, and managing disorders of the brain and nervous system including, but not ... Feb 19, 2021 ... The difference between an epidemic and a pandemic isn't in the severity of the disease, but the degree to which it has spread. British economist John Maynard Keynes spearheaded a revolution in economic thinking that overturned the then-prevailing idea that free markets would ... Mar 24, 2022 ... Settings ... An arrhythmia, or irregular heartbeat, is a problem with the rate or rhythm of your heartbeat. Your heart may beat too quickly, too ... Allergy occurs when a person's immune system reacts to substances in the environment that are harmless to most people. Jul 26, 2023 ... HIV (human immunodeficiency virus) is a virus that attacks cells that help the body fight infection, making a person more vulnerable to other infections and ... What is an AED Used for? AEDs are used to help those experiencing sudden cardiac arrest. It's a sophisticated, yet easy-to-use, medical device that can analyze ...