How many years did it take the modern engineers to figure out how the roman concrete was made out of?

explanation: we can only guess at how our actions may be perceived in the future. doing something really big like killing lots of people, saving lots of people, affecting the lives of lots of people is a sure fire way of being remembered in historical records. we can also make a difference in the history records by being a small influence on something bigger, whether that is as a civil servant, scientist or artist.

of course you could argue that we all affect history just as tiny cogs in a   bigger machine.

if you mean how do people influence our opinions of things which have already happened, then simply by writing a book which looks at things form a different perspective and trying to convince people that this perspective is more accurate or truthful. people do it all the time i.e. richard the third was a terrible or was he? plenty would disagree, it's just that their views aren't the most widely known.n:

hello!

according to the passage the most suitable options are two. the first one is "by leading the aef to victory in several key battles" like the battle of saint- mihiel and the battle of cantigny mentioned in the passage you copied here. the second one is "by the aef and allied forces defeat germany" since the passage says that his army destroy the german resistance in the meuse- argonne offensive. and also, "by insisting that the aef operate as an independent force".

hope this