Why was china not ruled by dynastic rulers for a period during the third century before the common era?

c. troops marched forward in close formation against newer, more accurate weapons

during the 20th century, the role of the vice president has evolved into more of an executive branch position. now, the vice president is usually seen as an integral part of a president's administration and presides over the senate only on ceremonial occasions or when a tie-breaking vote may be needed.