Charles Babbage, who was born in 1791, is regarded as the father of computing because of his research into machines that could calculate. Babbage's Difference Engine Number 1 was the first device ever devised that could calculate and print mathematical tables.
It may mean stopping or something getting in your way as your ultimate goal for example: say you want to get an A on your test, however you lose your study guide. Losing your study guide would be a stone in the field
The answer is for instance. This is the answer because the term "for instance" is sometimes used to give an example. In the paragraph, for instance is used to give an example of how cuckoos mimic other animals.
