Hyla never swears in front of her parents, but she frequently does so with her friends. this is an example of how language use is not guided by rules

The example can be understood to conclude that any language in a given situation changes its rules. An individual is guided by instinct and not by rule to behave or say certain things in a certain situation. In the presence of her parents Hyla implies a set of rule which totally changes when the situation changes from parents to friends. 

France played a key role in the american revolutionary war (american war of independence; 1775–1783). motivated by the ideals of the new nation which were inspired by the french enlightenment, as well as its long-term rivalry with britain and so as to avenge their territorial losses during the french and indian war, france secretly began sending supplies to the americans in 1775.