Master, can you tell me the usage of commas?<br/>case 1.<br/>Water<b>,</b> <u>taken in moderation</u><b>,</b> cannot hurt anybody.<br/><br/>case 2.<br/>Winston Churchill<b>,</b> <u>the former prime minister of Great Britain</u><b>,</b> was known for his witty answers as well as his leadership.<br/><br/>case 3.<br/>Silicon<b>,</b> <u>which is found in sand</u><b>,</b> is the second most abundant element on the Earth.<br/><br/>case 4.<br/>The city authority announced that <u>without a clear sign of economic recovery</u><b>,</b> the production could decrease further in the upcoming months.<br/><br/>case 5.<br/>In 1666, Isaac Newton discovered that <u>when pure white light passes through a prism</u><b>,</b> it separates into all of the visible colors.<br/><br/>Why does each of case 4 and case 5 not use paired commas instead of a comma?