1) The concept of civil rights pertains to the rights and freedoms that individuals possess as members of a society, including equality before the law, freedom of expression, and protection against discrimination.

2) The oldest known musical instrument is a flute made from a bird bone, estimated to be around 43,000 years old.

3) The President of the United States serves as the head of state and the head of government, responsible for leading the executive branch and representing the nation domestically and internationally.

4) The Yangtze River, also known as the Changjiang River, is the longest river in Asia and the third-longest in the world, stretching over 6,300 kilometers (3,915 miles). It holds immense cultural, historical, and ecological significance for China and the surrounding regions.