Questions

Since, the sentence starts with a subject, the next statement will carry a relative pronoun connecting the statements. S follows the opening statement. P will be the next statement which is mentioning the other feature of the man. Q will be the next statement as it describes another quality of man. Thus, R will be the concluding statement and thus form a coherent paragraph.

The correct formation would be, ‘The man who can play most heartily when he has the chance of playing is generally the one who can work very hard when he must work’.

Carbon monoxide (CO) is very dangerous because it binds with the haemoglobin more efficiently than oxygen does. It "hogs the seats" so that oxygen can't get a ride. And those CO molecules keep riding around, never giving their seats up to the oxygen. This means there is no way to get oxygen to the brain, heart, or other cells and those cells start to die. And finally, it leads to suffocation and even death of a person.