Do I correctly understand the usage of "e.g.","for example" and "for instance"? I found that "for example" is most commonly used. When the "example" is listed before the phrase "for example", we can not use "e.g." instead. Like in this sentence- "Many celebrities that have emerged from reality TV programmes, for example, come from the same walk of life as the viewing public.", it's not correct to replace "for example" with "e.g." here. But we can use "for instance" in this case. In contrast, if the "example" is listed after the phrase "for example", we can not use "for instance" instead. Like in this sentence-"These students had studied different types of angles, for example, acute, straight and obtuse angles, and discussed the notion of adjacent angles.", it's incorrect to replace "for example" with "for instance" here. But "e.g." will do in this case. These are my understandings. Are they correct?