Answer:
Norse
Explanation:
The first Europeans to arrive in North America -- at least the first for whom there is solid evidence -- were Norse , traveling west from Greenland , where Erik the Red had founded a settlement around the year 985. In 1001 his son Leif is thought to have explored the northeast coast of what is now Canada and spent at least one winter there.
In this example, john's whistling is serving as a discriminative stimulus.
This procedure, studied by Ivan Pavlov, shows a stimulus ( in this case the action of John's whistling) and a response ( the cattle run to the food trough).
Pavlov studied it with dogs. He realised that when a trainer fed them, dogs salivated. So, he presented the dogs with a "stimulus" ( the sound of a metronome) and when he gave the dogs food. After a few repetitions, when the dog listened to the stimulus, it salivated.
Answer:
In late 2019, a novel coronavirus, SARS-CoV-2, formed. This new virus had two important characteristics. First, it could cause severe disease and death in people. Second, it could easily spread from one person to anot
