I took the GOV4A exam in 2016. For the question about whether the modern presidency is one of vulnerability not strength, I discovered that modern presidents are from FD Roosevelt onwards. To get high grades, the examiners like to see loads of examples. For this you could talk about Congress reasserting its authority after Nixon's involvement in Watergate, leading to scholars suggesting that post-Watergate presidencies, particularly Ford and Carter, were relatively weak, Clinton's defeat of his healthcare proposals by his own party, Obama failing to persuade Democrats to vote for gun law reform, and the Senate refusing to hold a hearing on his Supreme Court nominee Merrick Garland in 2016. They will probably now want to see Trump mentioned as well. The failure of his skinny repeal of Obamacare which came down to one vote, McCain, might be worth mentioning.I'd then probably challenge the question too, as presidents usually show signs of strength in times of war, depression, and crisis, with Roosevelt being the best example of such a president. George W Bush also showed strength after 9/11 with the Patriot Act, signing statements, and Congress passing much of his legislation.Hope this helps