Answer:
The Supreme Court and other federal courts (judicial branch) can declare laws or presidential actions unconstitutional, in a process known as judicial review. By passing amendments to the Constitution, Congress can effectively check the decisions of the Supreme Court.
Answer:
The Percentages agreement was a secret informal agreement between British prime minister Winston Churchill and Soviet leader Joseph Stalin during the Fourth Moscow Conference in October 1944. It gave the percentage division of control over Eastern European countries, dividing them into spheres of influence.
This is somewhat of a variety answer, and so many answers can be put into play to answer this one, but from what I've seen, these seem like the best:
Cyber Attacks, Natural Disaster, Public Experience
I hope these is what you are looking for! Have a great day!