What are the three big changes that Shirky mentions to the media landscape? How do these changes affect journalists’ sources?

The conventions of a number of the states, having at the time of their adopting the constitution, expressed a desire, in order to prevent misconstruction or abuse of its powers, that further declaratory and restrictive clauses should be added: and as extending the ground of public confidence in the government, will best ensure the beneficent ends of its institution. what is meant by the phrase "further declaratory and restrictive clauses"?

How does the author's purpose affect his or her text structure

Dogs make wonderful pets because they us stay happy and healthy. the topic sentence is "dogs make wonderful pets." , is this correct? i keep doubting myself.