In Britain, strictly speaking, there are three elements in Parliament ― the Crown, the House of Lords and the House of Commons. The House of Commons is by far the most powerful and important of the three elements in Parliament and the Prime Ministers is the leader of the majority party in the House of Commons. After a general election in Britain, the Crown appoints tile Prime Minister who must be the leader of the party that has won the majority seats in the House of Commons. It is the Prime Minister who organizes the Cabinet and presides over its meetings. He or she actually decides on who will be the other ministers and so on. The work of each minister is always kept under observation by an unofficial "Shadow Cabinet" organized by the Opposition. The Prime Minister is the head of the government. He or she has the duty to report the government’’s work to the King or Queen, has the right to direct all the departments, solves the issues between them and approves the decisions of departments, which do not need to be discussed in the Cabinet. He has the last word in deciding government policy. The Prime Minister not only has the power of appointment but also has the right to reorganize the government, speak for the government in the House of Commons on important decisions and answer the questions of the members of the House of Commons. As he or she is the leader of the majority party in the House of Commons, he or she can control parliament and influence other parties. He or she is the most influential person in Great Britain and in recent years, strong Prime Ministers have shown a tendency to make policy decisions on their own, in the style of American Presidents. The Prime Minister works and lives in his or her famous residence, No. 10 Downing Street. h is named after George Downing, a British diplomat in the 17th century and has a history of over two hundred years as the British Prime Minister’’s residence. The inside of "No. 10" has been reconstructed to suit its purposes. In it there are the Cabinet meeting hall, the Prime Minister’’ s office and so on. It is here that the Cabinet meets; the Prime Minister receives foreign guests, meets delegations sometimes and does other work. There is an oil painting gallery in which the portraits of all the Prime Ministers, from Robert Walpole to James Callaghan, are placed. According to the passage, what is the function of "Shadow Cabinet" in Britain