I don’t really understand what a adverb clause is or what it’s asking can somone explain?

What is the meaning of the word checking as it is used in this sentence from the second paragraph of the passage?

Write a review of the first part of american born chinese that explains your opinion on the effectiveness of two different plot elements

Armed with invisible ink, a cipher system, and a passion to end the war and preserve the union, elizabeth van lew became butler's eyes and ears in the confederate capital city. truth be told, however, she became much more than that. she became a spymaster, the person responsible for running a network of agents, couriers, and safe houses that was very active during the war. in addition to the spying, elizabeth van lew continued to maintain her church hill home as a safe house and something of a local union spy headquarters. —the dark game, paul janeczko what is the central idea of this passage? van lew’s home was used as a safe house, which was critical to the confederacy. van lew had a passion to end the war and preserve the union. van lew was a spymaster, a leading force in the espionage activities for the union. van lew did not enjoy working for general butler.