单项选择题
Today,there are altogether（）departments of the U.S.government.
A.13 B.11 C.17 D.15
单项选择题 A president can serve（）term(s).
单项选择题 The President of the United States is elected（）
单项选择题 The writers of the Constitution worked out the Constitution worked out the checks and balances in order to（）
